Stickler
A ugly hack that takes the listening history of all your Last.fm friends, searches the web for the songs, generates QR codes for each. The resultant RSS feed is then dumped into Google Reader Play to make it a pretty slideshow.
Scan any song's QR code with your mobile phone as it flies by to stream the song to the phone. They're your friends scrobbles... in sticker form.
Team
APIs & Tools Used
Yahoo Pipes (of course!)
AOL Music Search
Google Reader Play