Yesterday's Mashup of the Day was a fun one for those who miss the good old days of command shells, goosh.org, "the unofficial google shell". Developer Stefan Grothkopp coded this on top of the Google Ajax Search API to give you a command shell for interacting with Google search queries. It lets you use many of Google's search types including web, images, news, blogs and video. It has a solid Unix-like feel from the time you get to the site, from the welcome motd message and the command prompt including username and directory ("email@example.com:/web>"). Type "h" or "help" gets you the full list of commands. Familiar names like "cd", "pwd" and "ls" all function, not to mention command history and tab completion.
There have been some similar web based shells and shell-like sites developed in the past. In discussing goosh, some readers over at Googleblogoscoped compared it to yubnub, the "social command line for the web".