I'm not sure if anyone's up for taking this on, but another board has a blog for their photo challenges. I think that would be a great idea for this too, then you can just bookmark the link and be able to get to everything easily. Plus, you can upload the pics to there, so you can still view them even after the siggy challenges are over. But again, someone would need to take the time to put it together and update it regularly with the new pics/polls.
Re: how do you track the EFF challenges, etc?
The challenges have a "Did you do it post?"
I'm posting the clothesline one tomarrow, since it was made last Wednesday.