G1: Essential Application
Here my most used apps on the G1:
Top Apps: NewsRob, the best Google Reader App on the G1, period. Astrid (with RTM Sync) for taskmanagement. iStockManager (with Ameritrade integration) to get rich 
WeatherChannel to not get wet. Scoreboard for live score updates (Bundesliga, NFL, etc.)
Messaging/Twitter Stuff: As I use multpile identities (strange, isn’t) I run Twit2Go and Twidroid as well as Twitta. Posting with PingDroid via Ping.fm, Pics go on the air usign PixelPipe. Blog News for WordPress are created with PostBot.
Multimedia: The one and only RockOn Player is the player of my choice. Last.fm player is aLastFM, SnapPhoto Pro for taking picture, Shazam for music identification (most impressiv app…).
GPS/Travel Apps: Google Maps is cool, but AndNav2 with offline maps is not bad at all, RadAlert a must. MyMaps Editor, Wikitude Travel Guide, Cab4Me and Qype, KlickTel give you a nice a warm feeling while traveling.
Other: Pkt Auction eBay to stay in sync with mother ebay, Quickpedia to lern new stuff, NubiNews (…). As Babyphone NoiseAlert gets the job done (in case you have kids and hate traditional baby phones). Edit the browser Bookmarks with Bookmarker.
Last but not least: For the next 2 month, PregnancyTicker is a daily used app on my G1 
Matthias
