Twitter: The official Twitter app is good enough for almost everyone. Along with giving you a clean, easy way to keep track of your timeline and updating your status, Twitter for Android also has a snazzy swipe down to refresh feature. Free.
Facebook: Facebook is finally decent on Android and now actually brings some unique features, namely the front page side-scroll of friend’s recent photos and a pull up notification window. Free.
eBuddy Messenger: A well-designed IM client that keeps you plugged into AIM, Google Talk, MSN, Yahoo, Facebook chat and others. Even better because it’s free. Free.
Tango: Tango is the best (and clearest!) way to video chat with your buddies, Android or iPhone, over 3G, 4G or Wi-Fi. Free.
Handcent SMS: Handcent puts SMS on steroids. It’s fully customizable (in look and theme) and gives options for popups and to even tweak individual contact settings. If you’ve never thought the stock messaging app on Android sucked, we won’t blame you. But after using Handcent, you will. Free.