[olodus]

Maybe I missed it but I don't see anyone mentioning Git blame. It is great tool to see how recently some part of the code you are working on were changed and by who, so you know who to ask. Also good to know what kinds of commits happens in your part of the code (if it is a good commit it probably describes what problem they were trying to solve). Hook it up to your IDE/editor (guessing it works with most of them, I have it hooked up with my vim) so you can see which lines changed in which commits.