Here are a few of my favorites:
historycommand will give you a list of the last 500 things you've typed:
Say you want to open the shell's current directory in a Finder folder. It's this easy:
$ open .
How often have you opened a Get Info window in the Finder just to know the dimensions of an image or other basic information about a file in a project? The Finder is fine, but you're already at the command line, so just use
$ file Default.png Default.png: PNG image data, 640 x 1136, 8-bit/color RGB, non-interlaced
Have you ever had a folder full of files that you've wanted to access through a web browser? You could setup Apache to do this by editing the httpd.conf file, or just enter the following command in the folder you want to access:
$ python -m SimpleHTTPServer 8000
Go check out Hockenberry’s entire post.