Here is a nifty idea. Use a couple of cheapo IR LEDs and a nimijack from your neighborhood RadioLove store and you can make your iPhone into a Camera Super remote.
DSLRbot ($4.99)is a simple playback application that plays WAV files. Interestingly, the WAV files it plays correspond to commands used on DSLRs infrared remotes. In turn, those can be used to make time lapse sequences, HDR bracketing and all kinds of similar tricks. Compare that to your over $100 Nikon or Canon Intervalometer.
Buliding the transmitter is easy enough if you have some soldering skills (or actually this would work as a great first project too). And it involves soldering two IR LEDs to a minijack. You than plug the minijack into your iPhone’s headphones socket.
You would also need the DSLRbot iPhone App from the iTune Store.