Good easy soldering projects like Bristlebots?
BEAM bots are cool..... a lot of them are pretty simple circuits - but they're effective. 
I also like how they have tiny little power harvesting solar cells :)

There's also heaps of different types and designs of BEAM bot's to experiment with.

Check em out on -> http://www.solarbotics.net/ 


(source: solarbotics.net)