My favorite apps so far are...
DocsToGo by Dataviz: paid $15 for full version (was 50% off) but it is full featured and easy to use. So if you use Word, Excel, Powerpoint alot on your desktop it is well worth it.
CompanionLink with DejaOffice: paid $50. I absolutely had to have this. I've been using a TREO for the last 8 years and was married to a product by Dataviz called Beyond Contacts which had outstanding sync ability. I was shocked to discover that their were so few effective options in the Android world to sync with my desktop Outlook (for which I extensively use for Calender, Contacts, Tasks, and Notes). Although I heard some complaints about this product, I found that if you follow the directions during installation and familiarize yourself with the options, it works great!
Handcent: very good text messaging app, has "Quick Text" feature that I use alot amongst a ton of other useful features.
LED light: nice simple flashlight. (Tiny Flashlight + LED had way to strong of permissions to suite me.)