Metapad is one of the most lightweight, simple, and yet powerful text editors out there. I love it for its tiny footprint, portability, multiple font support, block editing functionality, and transparent window capability. It also looks really nice :)
Before I upgraded this afternoon, I’d been using its previous version for at least ten years (via a recommendation from Chris Pirillo).
The latest version has a higher quality icon (which is really cool) and integrates fully with Windows 7 so it’s now my default text editor. Yes, you have to do a little OS-level tweaking and hacking to make that work…but it’s so worth it.