Tools for heavy lifting

Solving a tricky regular expression? The Rx Toolkit makes it simple. Trying code before burying it in your app? Use the interactive shells for JavaScript, Perl, Python, Ruby and Tcl. Or recycle your work as handy code snippets, stored in the Toolbox.

With Eclipse, I cannot simultaneously edit Javascript and HTML and have it validate both. I might switch to this for Perl/JS/HTML, when I get a chance to try it.

ActiveState - ActiveState Komodo IDE, End to end development of dynamic web applications - Dynamic Tools for Dynamic Languages