Use your computer as wireless keyboard for your Android device.

Keyboard for keyboard-less phones like Nexus One. Allow you to type on your phone using your computer's browser.
It works as ordinary input method. In example, you can use it in terminal or to type SMS.
Use WiFi for low latency input. 3G may be blocked by some carriers. USB connection works best, but require some technical knowledge and connected cable.
Source Code is available under GPL2 licence.