If not mentioned you can enter these challenges once...

Bitten by the bug2
Color throwdown
Cards for men
Critter Sketch
Craft your passion (Max 3 entries)
Crafty Boots  (As many entries you like.)
Crafty cardmakers (Combine with max 14 other challenges)
Cupcake Craft
The Cutie Pie (Every other, enter as many times as you like)
Daisy Doodles (Every other, digital images)
Donnas Den of Crafts
Fab's Christmas Card Challenge
Haunted Design House
House Mouse and friends
Incy Wincy
Inspiration Avenue
Karen Doodles (1st prize and  card of the week can only be won with their images)
Kreative stempelfreunde (Every other)
Lollipop Crafts
Make It Monday (MIM)
Mojo Monday (Prize: 1st sketch every month.)
Ooh-la-la (Every other)
Paper Cupcakes (Every other)
Paper Playtime (every other, 1st - Cricut Creation, 3rd - Sentiment)
Polly craft
Simon Says Stamp and Show
Stamps R Us (Every other, max 2 entries)
Stamp with fun
Sweet Pea Stampers (Every other, Sweet Pea or Ching Chou Kuik images only)
The Crazy Challenge (Max 2 entries)
The Pink Elephant
The shabby Tea Room (As many entries you wish=)
There she goes
Totally stampalicious
Whimsy stamps
2 sketches 4 you
Wild Orchids (Forthnightly, combine with max 2 others)

Anything Goes Challenge (As many entries you like)
Crazy Amigo
Creative Card Crew
City Crafter
Cards and Things
The Cat's Pajamas
The Cuttlebug Spot (Every other)
Digital Tuesday
Doodle Palace
Everybody art
Ladybugs Crafts Ink (Every other)
My Time To Craft
Ribbon Carousel (Must use anything on a spool, ribbon/twine/hemp/lace)
Papertake Weekly
Party Time Tuesday (3 entries, only 2 when "Anything Goes", must be a follower.)
Passion for Promarkers
Riley and Co - (Every other)
Runway Inspired Challenge (Combine with max 3 others. As many entries you like.)
Shopping Our Stash (Combine with max 12)
Stampavie and more
Top Tip Tuesday (Max 3 entries)
Try it on Tuesday 
Tuesday Throwdown
Veckans skiss  (Mostly LOs but you can enter with a card.)

The Pixie Cottage
All That Scraps
Cooking it up with Katie
Little Red Wagon
Color Throwdown
Creative inspirations (Combine with max 10 others)
Crafty creations (max 2 entries)
Divas by Design (max 2 entries)
Delightful Challenges (To enter twice, use a Digital Delights stamp.)
Flutter by wednesday (Must be a Butterfly, Fairy and Angel on the creation. Weeks with giveaway = 1 entry only)
Gingersnap creations
Hanna and Friends
Let's Craft and Create (Every other Wednesday)
Little Darlings Challenges (Every 2nd and 4th Wednesday. As many entries you like.)
My Mum' s Craft Shop (max 3 entries)
The Official Magnolia Inspiration Challenge (TOMIC) (Combine with max 5 others)
Old Magnolia (just for fun)
Simon says stamp
The Sisterhood of Crafters (Every 2end and 4th Wednesday. Max 3 entries.)
Paper Crafting Journey (Every alternate Thursday, as many entries you want)
Penny's Paper-Crafty (You can submit more than 1 entry =)
Perfect Sentiments (As many entries you like)
Prairie Fairy Fridays (Every other Wednesday)
Your next stamp

Aud Sentiments (Enter as many times as you like =)
CASE Study (Enter as many times as you like)
Charisma Cardz (Max 3 entries. Combine with 9 others)
Colour Create (Every other)
C.R.A.F.T. (Max 5 entries)
CropStop (Mac 3 entries)
Cute Card Thursday
Dare U 2 Digi Stamps (Must use a digi)
Divine Divas
Dutch Dare (Max 2 entries, combine with max 8 others)
Do You Stack Up (DYSU) (Max 3 entries)
Eat Sleep Stamp
Impression Obsession (1th and 3rd, must use their stamps)
Joan's Garden (Enter more than once)
Lili of the valley (Must use a Lili of the Valley stamp or die cut topper.)
Little Miss Muffet (Every other, if you use their images  theme is "Anything goes")
Meljens Designs (Must use their images)
Mo's Digital Challenges (Must use their images)
Moving Along With the Times
Off the Wall Craftiness
Our Creative Corner
ODBD (every other)
Pals Paper Arts
Paper Play
Papertrey Paper Dolls
Paper Romance
Pixie Dust Studio
Rainbow Lady's Challenge
Scrap it with a song
Sketches In Thyme
Stamp'n Doodle
Stampin' Bees
Stamping with the Dragon (Every other, enter as many times you like)
Sugar Bowl (must use a Sugar Nellie Image)
Tellens place
Terrifically Thrilling Thursday (max 5 entries)
The Paper Veriety
Play Date Cafe
Theme Thursday

Alphabet Challenge
Baby Bud Design
Bah! Humbug (x-mas cards)
Card for men
Card Makin Mamas (Max 2 entries, must be a card)
Christmas Stampin' All Year Long
Crafts 4 eternity (You can enter with 3 projects=)
Crafty Catz (1 entry only)
Creative Friday (every two weeks)
Daring Cardmakers
Delicious Doddles (3 entries each)
Fairy Fun Fridays
Fairy tale  (every other)
Friday Sketchers
Frosted Designs
Fussy and Fancy
Fun with Shapes and More
Glitter Geeks (Max 2 entries. Combine with max 9 others)
Hotshot Craft (Every third Friday)
If the Shoe fits
Just add Ink (Combine max 3 challenges, Primarily Stampin' Up! products)
Just Magnolia
Mami Doodles
Paper Cutz
Paper Makup
Paper Garden Projects
Polka Doodles (combine max 10 challenges)
Raise the Bar
Sew Many Challenges
Stamp Something
The Stamp Man (Every other. Can enter more than once with different work card, tag, LO etc)
Stampin' for the weekend (first and third/fourth friday)
Sweet Stampin (max 2 entries)
The TownScrapper

Allsorts (Max 3 entries)
A Gem of a Challenge (Every other)
Basic Grey (Every two weeks)
Card Patterns
Challenge up your life (Every two weeks)
Craftyhazelnut's Christmas Challenge
Crasy 4 Challenges
Create with Connie and Mary
Drunken Stampers (Every other)
Ellephantastic Challenges
Just some lines
Just Us Girls
Mark's Finest Papers (use their images and your into the draw twice)
One Stop Craft
Our Creative Corner
Secret Crafter
Stamp, Scrap and Doodle
Sugar Creek Hollow (Vintage/Shabby Chic. Max 3 entries)
Totally Gorgeous

Addicted to stamps (Every other.)
Anyone for Anya?
Corrosive Challenge
Doodle Dragon Studios (DDS images only)
Dream Valley (Every other. You can enter 3 times)
Here comes the boys  (Every other. Max 3 entries)
Ink on My Fingers
I did it creations (Robyn's Fetishc)
Just Cute Bears
Kenny K's Krafty Girlz (To enter the price draw you have to use KennyK images)
Lovely hÄnglars only
Magnolia Down Under
One Stitch at a Time
Paper Sundaes  (Max 3 entries. Combine with max 9 others.)
Pile it on
Practical Scrappers
Queen of my craftroom
Quirky Crafts  (Combine with max 5 others)
Sketcy Colors
The Squirrel and the Fox  (Max 2 entries)
Stamptacular Sunday (Must include stamping)
Sunday Sketch and Stamp (Every other Sunday)

Twice a month
ABC Challenge
Bird is the Word
Desert Island Crafts (Every 1st and 15th)
The Emerald Faeries (Max 3 entries)
Forever Friends
Kort o Mania (max 3 entries, combine with max 5 others)
Oldie But A Goodie
Panduro Hobby (Max 1 entry)
Pollycraft challenge
Resonable Ribbon (Every 1st and 15th, must use ribbon/lace/trim)
Sketch and stash challenge

AiFactory (1st of every month and you have to use their stamps)
Baby Bud
Bildmalarna (only their stamps)
By the Cute and Girly
The Crafty Pad
Crafter's Companion Monthly Challenge (2 entries if you use their stamps)
Crafting Life's Pieces (CLP) (Sketches, 1 entry only)
Creafter's Companion USA - (You have to use their stamps)
Creatalicious 15th each month
Christmas Cards all year long
Hooked on craft (First Monday)
I Brake for Challenges (Max 2 entries)
Joanna Sheen (You must be a flollower.)
Let's Ink It Up (Digi images are not permitted. Max 2 entries)
Marianne's Design Divas (Every 15th, must use Marianne's Design products. Enter as many times you like.)
Mema's Crafts (need to be a follower)
Midnight Madness Sketch Challenge
One Sweet Challenge (1st Sunday. Must use a Sweet Pea stamp)
Papirpikenes verden (1th each month. Combine with max 1 other, max 3 entries)
Sparkles (15th each month. Max 3 entries.)
Sundays with Crissy  (1th each month. Max 3 entries)
Thats just so cute
Trykkpressa (Max 3 entries)
Virginia's View
Whoopsi Daisy (Must use a Whoopso Daisy image)

Scrappy frogs (Every three weeks)
Wild Orchid (Combine with max 2 others)

Norske utfordringsblogger
Aud Sentiments (Antall bidrag bestemmer du selv =)
Kortgleder  (Den 1 i hver måned.)
Papiravisen (Max 3 bidrag)
Papirdokkene (Max 3 bidrag)
Sketchy Colors
Scrappehuset (Kan ikke kombineres med andre.)
Trykkpressa (Norsk stempelblad) (Max 3 bidrag)

Closed challenge blogs
A spoonfull of sugar
AI Factory
Cat's corner
Created by hand
Cowgirl's Sunday (you can enter 3 times)
Cutie Sunday
The Catered Crop
Just christmas and birthday cards
Little Paper Shop
Limelight Papercraft (every other)
Magical Monday
Mixed Media Monday
One Powerful Hour
Pear Tree Designs (max 2 entries)
Scrapping the music
Treehouse Stamps
A Crafty Little Place
Wednesday Stamper