1. Insights - Googling inside your admin panel when writing new post.
2. NM Delete Revision - Useful plugin to decrease export file size when you planned to migrate all your posts, comments, etc.
3. DB Cache - The fastest cache engine for WordPress, that produces cache of database queries with easy configuration. Better than WP Cache or WP Super Cache.
4. WP Note - Cool wordpress plugin to catch readers attention on your posts.
5. WP Twitip ID - adds a field to the comment form for a user to add their twitter username.
Okay, it's enough for now.