Smashing Magazine has put up a review of 35 useful source code Editors. Those editors can be quite useful for editing HTML, CSS or programming code or just as a notepad replacement.
Here are some of my favorite picks from the list most of which I currently use too.
The one editor that finds a worthwhile mention from my end if Eclipse which I use to create java and PHP projects. I use eclipse for creating WordPress plugins and client projects because of the better management features it provides me with.
Would love to know which is your favorite editor.