If you ever needed confirmation that your iPhone is your PC away from home, this is it. VNC Viewer is an app that lets you use any computer from your iPhone or iPod Touch.
The app gives you full control, so you'll be able to run programs on your PC, access and edit documents, and change settings on any Windows, Mac OS X, Linux or UNIX computer, all from the comfort of your iPhone.
Video junkies will be pleased to note this means you can finally view those Flash-based websites even though the iPhone still doesn't support Flash. Go, loopholes!
You can use the same iPhone gestures - tap, drag, pinch - to view the computer windows, including pinching to zoom, or you can switch to a mouse button mode with virtual mouse buttons and scroll wheel superimposed on the desktop view.
Once you download the app from the App Store, you'll also have to install a desktop version on the computer to be controlled, such as VNC Enterprise Edition (for a separate fee).