Skype – free IM & video calls
My family lives abroad so this is a no-brainer and the best way to chat with them either via video or just with voice.
I’ve been using this for years and it works well enough on Android in a pinch.
If you’re a texting fiend, this fully-functional SMS app might be a better option than the in-built messages app on your device.
Dolphin – Best Web Browser
Once again, not all stock browsers are made equal, so if your one is giving you trouble, try Dolphin instead.
Tether to Mac, PC and even games consoles… and you don’t need to be rooted!