[META] How about weekly contests in classification?

So maybe we could get a weekly thread when someone sets a dataset and a problem of classification. Then we hack some solutions and see who gets the best results in said week - so we all can improve our practical knowledge.

These could be simple OCR contests, object recognition, financial prediction etc.

What do you think?

EDIT:

So I've decided to create the first challenge:

http://www.reddit.com/r/MachineLearning/comments/22q2q4/biweekly_classification_challenge_1_car_detection/

Feel free to get to work!