Lets face it, unless you have a photographic memory, no developer can remember all the different functions, options, tags, etc. that exist. Documentation can be cumbersome at times, thats why I like cheat sheets.

I have been reading up on Subversion - an open source control product, my friend Tim provoked me into this. I recommend checking out the Subversion Book (html, pdf) - which is a draft of an upcoming book Version Control With Subversion (O'Reilly & Associates).