I love widgets. Easy to use, and keeps the code nice and clean. But there's one small problem – they are the same everywhere on the site.
It would be great to be able to define different sets of widgets for the index, single posts, pages and archives.
Take "recent posts" as an example: it's a bit redundant on the index, where the recent posts themselves are hanging out, but excellent for telling someone who was referred directly to a post what else is going on at the site.
So, I think it could be a neat feature. If it can be done with a plugin.