Is it possible to connect your USB mouse to your Android device? Hmm... I can't say all Android devices could be easily support external peripheral device such like desktop computer does. But for smartphone and tablet, it's not impossible. In this video below, you'll be amazed how the Samsung Galaxy S2 can support mouse.
This mouse connects OTG cable to Galaxy S2 and was able to use it through the OS and applications. Switching home screen panels, navigating the browser, Android market and the whole OS worked like a charm. pretty awesome!