It is not often I write about other NXT projects - but this one from Steffen Lindner in Germany really caught my eye - due to its simplicity and the amazing lateral thinking that has gone in to this:
Who needs an IR-Link to bridge between NXT and RCX when you got this?
The solution has an RCX light sensor reading the LCD of the NXT, and a NXT light sensor reading the IR port of the RCX. Impossible? You need to see the video to believe it!
More info on Leggor.de