Just used my new Chicago Electric chainsaw sharpener that I got for my birthday. It really impressed me for the type of work I do, and the price was great. Harbor Freight has them at just under $40 right now.
Tolerances aren't all that great, but what can I expect for the price. A little care in use, and it sharpens the chain just like I want it. Plus, they've made some pretty good improvements over their last model (example - the hand break you can't see in this picture that allows the user to clamp the chain when lowering the handle instead of always having to loosen and unloosen a knob to do so). It seems to be built a little more ruggedly, too.
Now I just have to go make some more sawdust with my chainsaw!