I've got a couple of feature requests:

 - When entering a question, search for similar questions or similar tags on sister sites.
 - Allow a community upvote and downvote of the a moderator's question flags.

I'm frequently surprised about what questions fail meet the FAQ guidelines for any given SE site and get a moderator smackdown. For example, it seems that "domain registration" questions are off-topic on ServerFault (even though the FAQ says "networking" Q's are OK, and there's of "domain registration" Q's under that tag). :-(

The topic separation through SE seems to harm the UX has much as it helps, especially as many of the SE sites have clearly overlapping topic areas such as this (is it right for "server fault" or "web masters").

It would be nice if the sister sites were searched for similar questions and tags before posting so that a better forum can be found. Also, it would be nice if the community, as well as the moderators were able to exert some say on whether questions are right for a particular forum (allow us to +1/-1 the off-topic flagging).