My Favs:
Wikiamo - Wikipedia interface
Weatherbug and WeatherEye - 2 Weather apps? They fill different niches in weather info presented. WeatherEye is better for a quick glance at current conditions and forecast, while Weatherbug allows you to look at satellite photos, and is very granular when selecting weather stations.
Flixter - Shows what's in theatres near you, with showtimes, ratings, trailers, etc. Also shows what's on DVD. Great app
i.TV - Love this app too, Shows local tv listings, with ratings and previews, allows customized channel lineups (you can hide the channels you don't get, or want to see), You can show only movies, or shows in HD, sports, specific genres. Awesome.
WiFinder - Use this to browse and connect to wifi hotspots. Shows signal strength, and which ones aren't secured.
JellyCar - Fun game, interesting physics
Rogue - classic roguelike port, very cool
All of those are free apps, at least they were when i got them. The only app i've paid for is Enigmo, and it was worth the $2 i paid.
Lets keep this thread alive everyone.