The emerge of Aptana plug-in make me seriously consider install Eclipse on my development computer. Here is what I do to take advantage of Aptana's superior JS edit functions in my Visual Studio web project.
1. add a simple eclipse project under my web application development folder (this will only add one file to my project: .project);
2. associate "*.aspx" to "Aptana HTML Editor", "*.css" to "Aptana CSS Editor", "*.js" to "Aptana JS Editor";
3. add my JS library to "Code Assistant Profiles";
Please look at the screen-shot to see what Aptana can do: code auto-complete with documentation of parameters, tree structured outline of code file, code refactor, code snippets, to name a few. (a side note: also get "Firebug" for JS and CSS debugging in Firefox.)