Community contributed stickers & decals!

In the future it would be wonderful to see a community designed sticker selection!
Whether they be picked by Dice, voted by the community, etc. These could be given as rewards for playing Portal modes with others, unlocked with unique in-game challenges, earned for playing in Friday night battlefield events, Added to the store with a percentage of sales going to the creator of said sticker, or even a charity of their choice.

I feel there is a lot of potential in this!
Feel free to share your thoughts, or even stickers you'd like to see.