So one common problem I have is writing code at a macro level---refactoring things in multiple files. Notepad++ used to make this easy with it's fast and powerful find/replace in folder feature. Textmate's built in find/replace in project is painfully slow.
Grep & Sed don't cut it either. I've been using some custom written perl scripts for my needs. But today I discovered ack & AckMate. Problem solved. Really tight integration with TextMate (though the default 4 key shortcut is terrible--need to change that).
This is probably something I would have learned faster had I been doing more pair programming with senior devs.