On Windows, I use Notepad++ which has the great feature of when I select a word, all instances of that word are also highlighted in the same document. I have found it very helpful for finding patterns in giant log files.
I am wondering if there is a similar feature in a text editor on the Mac. I have looked into the documentation for TextWrangler and TextMate to no avail. Hopefully there is a way to do this so I can be more productive when working on a Mac.
Note: in Notepad++ you do not have to do a keyboard shortcut to make this work... you just select some text and it does the highlighting for you automatically.