The file editor when editing Web Resources is as basic as they come in CRM 2011 (and all the previous versions). It would be such a nice gesture for Microsoft to create an editor with a few basic features like syntax checking and formatting.
Microsoft have yet to do anything in this area so one someone got bored of waiting and has started the process by creating the Shrpr Web Resource Editor. You can read more about the editor in this blog post and you can download the solution (a CRM solution which you can import) here Downloads
It has features like
simple code completion
I think this is a really good start because syntax highlighting is very useful and the matching braces is fantastic. Hopefully if people start using it and giving some feed back he will continue to work on the product.
So thanks Roman Gebesmair and keep up the good work