I was reading the Gizmodo story on the fake flashlight app that was actually a tethering app:
http://gizmodo.com/5592521/how-a-guy-tricked-apple-with-a-disguised-iphone-tethering-app
It's been pulled from the app store, but apparently it actually worked.
Hopefully this will show up as an app for jailbroken phones, but another idea would be to make the app source/package openly available so any developer can compile and install it on their own phones and their friends.
I'm too busy/lazy to take a shot at it, but it'd be a nice thing for someone to do. Anyone want to write an open source tethering app?