Looking for plugins like these

I’m in the process of converting my site from an old *nuke install over to WordPress, and am trying to find some plugins that have the following functionality:

1) User themes — is there any sort of plugin that allows a user to permanently set what theme they want to use in their profile settings? (I’m not talking about a temporary theme switcher/previewer).

2) Glossary/dictionary — one that allows you to set categories, and input terms with definitions.

3) Store that ties into outside affiliates — we have a store that ties into Amazon, Posters.com, and several other affiliates. It allows us to set up categories, and then input any affiliate product that we want. Does anything like this exist?

4) What’s the best downloads plugin? We have several categories of downloads (wallpapers, bookmarks, notecards), that having ratings and reviews.

I’ve been searching around, but not finding a lot for the above items. Any suggestions are appreciated!