IR LEDs

Do you know any good and easy project which uses the IR LED pair on the Arduino???
Thanks!

see this link:

I found this during my research:

http://letsmakerobots.com/node/4428

Actually pretty easy. Dagu now sells a premade board for $9

http://www.robotshop.com/dagu-compound-infrared-sensor-4.html

I might order this, but the shipping cost is more than the part itself, which is a real pet peeve of mine.
Seeed Studio will ship similar sized items for $3... oh well