I've recently started using the Stihl 2-in-1 EasyFile for chain sharpening and I'm very impressed with it.
http://www.frjonesandson.co.uk/products-page/stihl/sharpening-equipment1/stihl-2-in-1-easyfile/
It's a manual filing guide that holds a round file for sharpening the chain tooth and a flat file for taking down the raker height at the same time. No more having to check raker height afterwards using a different guide. With the 2-in-1 EasyFile, an arrangment of guide bars that run parallel to the files and which rest on the chain behind and in front of the tooth being sharpened keep the unit at the correct height in relation to the tooth and raker. The handles at either end of the guide are shaped to help you keep it at the correct angle. Symbols on each handle make sure you're using the correct side and holding it the right way round for whichever 'side' teeth you start with, then you flip it over to do the other set. The files are replaceable when they're worn.
Good video of it in use here: -
http://www.youtube.com/watch?v=p57zA9OOjs0