I found this article discussing a quick way to sort your bash history and see which commands you use the most:
cut -f1 -d" " .bash_history | sort | uniq -c | sort -nr | head -n 30
It really opens your eyes as to which tasks you should create aliases for and which ones you should cronjob away completely.
I'd love to see a ServerFault list of recommended command line aliases that save you time on the job. What have you got?
Between us, I'll bet we can save every user who reads this post at least 10 minutes a day. (Minus the first day wherein they waste all of their time reading ServerFault instead of doing their job of course!)