and maintainer of:
In this article listing a top 10 of tools, Perl is rated #1.
Some of the other tools in the article are a bit wierd, but I guess all would have their own personal top 10 of favorite tools.
I think mine (just of the top of my head) would look something like:
2. Terminal.app or xterm
5. grep (and variations)
10. OS X
The list might look different tomorrow