Also, noticing TextSecure, it's great, but I have personal gripe with it -- you can't use it without using Google play, and that means irrevocably pairing your phone with Google account and therefore some identity. Would it be that much of a hassle to put APK on f-droid? Software that's supposed to be secure but requires you to have Google account is a sad view.
EDIT: of course, after the (de)cryptocat debacle, using TextSecure without reading the source code might not be a good idea. Homepage of "security" software like that should always include page about security: what algorithms it uses, stuff like that.