* BubbleUPnP: Streaming UPnP media (music, videos, pictures) over the internet. It's the only nice way I can find of managing music on a computer and accessing it through the internet. (I don't care much for any of the cloud music services.) https://play.google.com/store/apps/details?id=com.bubblesoft...
* Lightning Bug: Really nice background ambiance player. https://play.google.com/store/apps/details?id=com.media1908....
* QuickPic: Fast and clean photo gallery app. (Way better than the Gallery app in 2.x) https://play.google.com/store/apps/details?id=com.alensw.Pic...
* FX File Explorer: My file manager of choice. Great looking, good amount of useful features (the Dropbox integration is top-notch). https://play.google.com/store/apps/details?id=nextapp.fx
* AdAway: FOSS hosts-based ad blocker. Requires root. https://play.google.com/store/apps/details?id=org.adaway
* Hacker's Keyboard: Full PC-style virtual keyboard. Great for SSH and local terminals. https://play.google.com/store/apps/details?id=org.pocketwork...