Neat little devices from Sparkfun: Four 7-segment LED charaters, controlled via simpe "print" commands across a single bit from your Arduino. Only $13+ p&p.
Introduction, "how to" and demo Arduino programs....
Sparkfun part numbers (only difference: Colors. but listing all for search engines!)
COM-09764
COM-09765
COM-09766
COM-09767
Enjoy!