So as I was in the middle of writing another post tonight I needed to snap a quick screenshot and I ended up getting a nice little tip from icelander in #mac on irc.freenode.net (using Colloquy btw, which I need to blog about as well).
I knew that I could take a screenshot of the whole screen with Shift + Command + 3 and that I could grab a lasso with Shift + Command + 4 but I didn’t know how to just grab the contents of one window. Anyway, it turns out if you press Shift + Command + 4 and then hit Space, your cursor turns to a camera icon and you can grab just the contents of one window.
This whole feature is really nice because I don’t have to worry about finding somewhere to paste it like I do on windows (although the shortcut key there is more logical – Alt + PrintScreen), it just appears as a ready to use PNG on my desktop.
Any other key combinations for capturing screens that I missed?
Update: I hadn't noticed but Paul also suggested this.