OneNote. I use it for taking and reviewing notes.
Foldersync. Sync the files I want to the cloud/FTP servers I want.
HDweather: Great and accurate weather and radar widgets
Pure calendar widgets plus Public Folder sync to see my work calendar in a widget.
OSMand for offline maps with tracks and routes
Gasbuddy and Waze for when traveling and wanting to keep an eye on things
Battery Monitor Widget, so I know how well a charger really is charging.
Llama for set the volume and screen timeout based on where I am, and what I am doing.
Cellica Database to keep a couple of Access databases available on the phone.
TeamViewer to remotely control any of my PCs.
Google Keep synced wife my wife's account so I can add beer to her grocery list.