QuickOffice Pro (Office Suite also PDF reader)
Evernote (notes app and also use it with the Skitch app too)
Google Docs (Office Suite in the cloud)
Google Maps (maps and navigation)
Dropbox (Cloud storage and public file sharing)
Google Goggles (great for QR/Barcodes)
AppGarden (replaces dozens of tools)
Realcalc (a better calculator)
Google Voice (Primarily for the free text messaging)
Google Talk (IM to communicate with)
Key Ring (stores customer value cards)
Shopper (shopping list creator)
CameraZoom FX (The best camera app IMO)
Google Reader (RSS reader)
ReadItLater (for off line web article reading)
BeFunky Pro (photo effects editor)
PicSay Pro (looks like it is stupid but it's great for marking up photos)
DoggCatcher (podcast player)
TuneIn Pro (Radio app)
Google Play Music (cloud music player)
PowerAmp (local music player)
Google Play Books (eBook reader for Google books)
Kindle Reader App (eBook reader for Amazon books)
Wunderlist (cloud based list maker)
CamScanner (scans and converts docs to PDF)
You should find many of these apps liste phone section of this website ... as well as a tool to do a search and compare of cell phones (model and vendor) - -