Quite a few people I know who use a Mac like to take advantage of the UNIX-like Terminal from time to time. I use it for remote logins to the computer clusters that do my PhD work for me, but there are all sorts things you can do using the built-in command line utilities, and for certain automated or repetitive tasks it’s often far quicker than using a graphical interface.
I recently found a great application called TotalTerminal which takes control of OS X’s inbuilt Terminal app and allows it to bring up a terminal ‘visor’ just by pressing a shortcut, a bit like the console in iD Software games like Quake, Doom etc. This is very handy if you want quick access to the command line regardless of what else you’re doing at the time, and it’s very customisable too. I use ‘Apple+§’ to bring up a terminal from the bottom of the screen, so that I can quickly use SSH to check on my simulations.