A while back I bought a couple of Twist sponges/euro cloths. The boxes had directions printed on them for how to turn the box into a birdfeeder. I made two little birdfeeders. I do wish the pattern had used up more of the box, and the resultant birdfeeder was a little bit bigger, but it's definitely a unique idea on Twist's part.
The two birdfeeders in action (note the annoying construction behind my building):
Twist lets you upload photos of birdfeeders to their gallery so I just submitted mine :) There's...er.. only one up there right now so hopefully they'll post mine.