I use k-9 mail over the native client (+AGP), Aldiko for (free public domain) ebooks, ebuddy for multiprotocol IM (or trillian beta), ES file explore for organizing files, Shazam, Notification notes cause it's handy, ShareQR and Quickmark on the PC to copy/paste to PC, Barcode and Mobile Barcoder plugin for Firefox to get it done the other way around, I also use VLC remote (tricky to set up), I have Wavsecure, because I got a lifelong membership when it came out and AK notepad for additional note-taking and also gesture search, because it's convenient Zumo drive for cloud services (not a fan of the cloud though), but will soon switch to ubuntu one.