Ravioli Paint 2 - I swear this thing's the most powerful free image editor I've come across. It even includes exporting to *.ora file format (which is a rarity!) so I can continue my work on the picture in Gimp. There are, however, a few UI flaws that bug me.
Drawchemy - The alchemy drawing app on the phone. What else can I say?
FTP server - (from FDroid, not sure what happened to the google play link for it) I like the fact it has both an anonymous read-only view and a read/write view.