Some people (like myself) have negative rep for many silly reasons, or because some people didnt know the difference between a bad-red rep and a good-green rep. But no-one cares about rep anymore..i think
Spoiler tags we don't have yet. I too suggessted this a while ago. I think it'd be great if we had some, for spoilers to mangas and for hiding sigs if we have a large one for instance.
I guess we'll have to wait and see what Tom will do.