Rainbowth is a Sublime Text 2 plugin that automagically highlights matching parentheses in Lisp source code. While the name does imply a certain sequence of colors, the palette used to paint them is entirely configurable; nonetheless, the effect is perhaps best demonstrated when viewed with a theme like Tomorrow Night:
It took about three hours for Racket to grow on me. I know with a fair amount of certainty that I'd like to master it, but the structure is going to take some getting used to. This plugin attempts to overcome one of the primary barriers to entry, that of not being able to tell what's related beyond the matching of a single parenthetical pair.
Cloning the repository directly into your Packages directory is simplest.
git clone https://github.com/andkerosine/rainbowth.git Rainbowth
The palettes setting is a mapping of theme names to the list of colors to use for painting parentheses while using that theme, outermost first. When using a theme not specified, the default ROYGBIV sequence will be used.
The plugin does not appear to cause any noticeable lag, but I didn't test it on any massive files. Still, there are a few places it could be improved. At present, only the current block is highlighted, and this happens after each keyed parenthesis (to ensure pasting works as expected). While this does suffice for the overall purpose of this plugin, highlighting the entire file seems like it'd be more aesthetically pleasing. This is made non-trivial by the fact that keeping track of each block would require attaching an index, which would glitch when inserting a block between two existing ones.
Comments, criticisms, and code are all eagerly welcomed.