I was checking over my fresh copy of the Lego Education catalog I got in the mail yesterday and I noticed a couple of pretty cool robotic arms. Normally, I just glance over them mainly because they are super expensive and why buy one when I could build one. The big one called Brutus is $3500 and pretty detailed and would be fun to play with, but more fun to build.
Then I noticed the smaller one called Rooster. Rooster isn’t really a robotic arm, but an R/C arm. I took a glance at it and it looks like it can be fairly easily made using five PF motors; two driving motors, one arm lifting motor, one gripper tilting motor and one gripper motor. You could really get lots of bang for the buck. And of course, you could throw a NXT and some servos and some sensors in it to make it programmable.