Dive into the archives.
- WeBot
Stream music and photos from multiple computers over the web to your iPhone.
http://webot.com
- RDM for iPhone
Remote Desktop for Mobiles allows you to connect to your PC from anywhere, from your iPhone.
http://iphone.rdmplus.com
- iRed
iRed allows you to control any IR device from your iPhone, assuming you have a USB IR device as well.
http://www.tinbert.com/iRed2/iPhone/
- iTunes iPhone Remote Control
This app is alpha, and is NOT for the faint of heart, involving a good bit of installation and a few hacks. It DOES work though.
http://www.scottbender.net/wiki/bin/view/Main/ItunesIphoneRemoteControl
- Telekinesis
Telekinesis allows you to remotely connect to your Mac using your iPhone… awesome!
http://code.google.com/p/telekinesis/