Sublime Text ist a beautiful, lightweight and very customizable editor for all kinds of programming and markup languages. It has a portable version that you can e.g. put into a Dropbox folder to synchronize your installed plugins and user settings over multiple computers.
As a side product of a student project together with my friend Johannes (who wrote all the complicated lowlevel stuff), I created a small plugin for Sublime that allows you to send MAXScript commands directly to 3ds Max. Before when developing MAXScript in Sublime you would have to switch to 3ds Max and run your script in its editor or press a button to launch a startup script or whatver; now you can simply evaluate your code directly from Sublime.
If you like MAXScript and Sublime, you will love this!
Get detailed installation instructions by following the download link: