ConTEXT

I've found this great text editor for code development. It has loads of highlighting stylesheets but most importantly for me it handles CSS, JavaScript and HTML very well, although I haven't managed to find one for ASP. It's also free which is a great bonus. I've tried a few editors like this but this is the first one I've found that supports so many programming languages for free.

Update: Tell a lie there is a highlighter for ASP but having using ConTEXT for a few days now I've found that the JavaScript highlighter is actually much better for ASP than the ASP specific one. At least it is if you use server side JavaScript like me - I haven't tried it out with VBScript yet (and I'm not likely to). You still get that server side vrs. client side JavaScript confusion but if you code this way you're probably over that anyway (I am finally-ish).