One of the things which you are likely to have to do when you change platform, in my case from Windows to Mac OSX Mountain Lion, is to learn all the keyboard shortcuts. Would it not be nice if you could get an app which can list any shortcuts in the context you are in? Well it out there, and it is free!
Introducing CheatSheet – a free app for your Mac
It is a very easy and very handy app which when you hold down CMD key (if you use a PC keyboard for you Mac, as I do for now – it is the windows key on the left side of your keyboard right next to the Alt key) for some time and voila, you will get a list of the current offered key shortcuts – nice!
You simply need to visit this link: http://itunes.apple.com/app/id529456740?mt=12 and perhaps install it through app store. After it is installed first time you will need to allow the app to listen to keyboard shortcuts. You will be prompted first time with instruction, so just go ahead install.