I've voted up Qiaochu's request. Another idea that I was discussing with somebody (Scott?) a while ago is a user preference to ignore any question that you've voted down. I feel like private tags would be feature creep.

@fedja: I'm not sure if this is what you want, but you can check the "hide ignored tags" box in your user preferences page to make it so that questions with ignored tags don't appear at all (rather than just being grayed out).

Hmm, interesting idea. It sort of has the ring of the "Journal of Stuff I Like" (some post on "God Plays Dice" a year or so ago). I could decide that if Greg Kuperberg thinks a question isn't worth looking at then I'm not going to look at it either, ditto a few others that use the site. I can see some potential for that idea.

Except that, of course, it wouldn't work because the system isn't designed to be used that way and there are too many changes that would need to be made to ensure the system wasn't abused.

I retagged this because I have tag-removed blocked, and this question's going to be closed soon anyway.

I think you may have somewhat crossed a line there since you're retagging (an admittedly bad) question, just to serve your own purpose.

1. No one is updating the sticky post because no one has got around to it. Feel free to add links to mathoverflow specific feature requests you've seen elsewhere.
2. If you post a feature request on meta.SE (not meta.SO -- that's the Stackoverflow equivalent of this site), and post it in our sticky thread, I'll happily vote it up even if I don't particularly agree with the need for the request! (That applies to all mathoverflow residents, of course.)