We posted about the Redeye mini a while back -- it's an IR dongle that hooks up to the audio port on the iPhone to let you control any IR device (your TV, DVD, or whatever else you've got) with the touchscreen on your phone. You need a free app from the App Store to use the dongle and it doesn't look like much, but ZDnet actually says it works great, controlling multiple devices with ease. You can also set up various activity settings on the remote, and then customize buttons to do whatever you want to do.
So it looks like this is a very workable solution if you're interested in using your iPhone as a remote, especially compared to something much more expensive. At just US$49 (though of course you'll need an iPhone), this easily beats most other touchscreen remotes. Thinkflood is taking orders on the dongle right now.