In response to the rage-of-the-moment shell history meme, I present my list, which looks different than a lot of peoples':
149 cd - Well, duh
104 ./run.sh - Occasionally to run JBoss (I have to have two JBoss servers running locally, and when I do a complete recompile/redeploy (not often), I must restart, as ant fstats the ever-loving shit out thousands of files (multiple times, per, 'natch, cause it so superior to make) at the same time JBoss is hot-deploying (twice) and my machine just dies), but more often to run the application I'm developing.
88 tail - To read log files (were I on OS X, Console.app would be the way to go)
84 ls - Well, duh
73 git - I commit a lot, I diff alot, I stat alot, and I blame alot. You should, too
57 sqlshell.pl - Awesomely awesome command-line SQL client written by my co-worker and enhanced on occasion by me. I'll probably steal it when I leave this project, and I wish he'd put it up on sourceforge
51 jobs - To find out which JBosses to kill (frequently executed in the wrong shell window)