Google+ (Android) is still in active development and not yet available to everyone. You need an invitation to sign in.
Google+ for mobile makes sharing the right things with the right people a lot simpler. Huddle lets you send super-fast messages to the people you care about most
MOZAT is probably the most powerful mobile social tool on this planet! It connects you with your friends no matter what phones they use.
Features: Facebook, Twitter, Windows Live Messenger, Yahoo! Messenger, GTalk, Facebook chat, File transfer, Delivery status report, Social games (Ocean Age, Texas Hold'em, and more)
Twitter (Android) - The official Twitter client for Android phones!
Discover what’s happening right now, anywhere in the world with the official Twitter for Android application.
Realtime search, trending topics and maps show what's happening now.
Tweet, send DMs, share photos, videos and links to your friends and the world
SoundCloud - Record, listen and share your sounds on the go with SoundCloud Android.
With the official SoundCloud Android app you can capture your sound and share it privately or publicly on Facebook, Twitter or even use it to check-in on Foursquare
eBuddy Messenger - Get the best Instant Messaging Application!
Fast & reliable
Chat on multiple MSN (Windows Live), Facebook, Yahoo, AIM, ICQ, GTalk, Hyves & MySpace accounts
All IM buddies in one list
Runs in background
Messages sent as data, not SMS/Text
New in 1.8
XDA Mobile Application! Free! OMG! *Special announcement: many that are leaving reviews are remarking that we have removed features from the free app. This is not the case, in fact, we've recently added two features (Legacy support and the ability to choose landing behavior in a thread)