Teamviewer today released their free-for-personal-use
Teamviewer App for Android (Beta; click "Mobile" to download).
Install it on your Android phone, and the appropriate server software on your PC or Mac (or anybody else's PC or Mac; click "Windows", "Mac", or "Linux" to download), start up both, exchange ID and password, and you can remotely operate that PC or Mac, from your Android phone.
Ideal for 24/7 access to (the power and the storage of) your own computer at home, wherever you are (not necessarily via Wi-Fi!), without having to schlep around a laptop or a tablet. Or to help someone else with computer problems: you can instantly take over their desktop, while they can see what is happening on their own screen.
Its speed depends on your connections. Wi-Fi is (obviously) fastest.
The screen real estate on a phone sucks of course. So you won't suddenly be doing any heavy desktop work on your phone. But
Teamviewer is an ideal backstop, imo.