That module looks pretty nice from the Perl side of things. JS will count too though. This is anecdotal but prototype generally comes in last out of the major libraries most devs would choose to use. YUI, dojo, MooTools, MochiKit, jQuery, and ExtJS all have better reps and from what I understand, it's deserved. Modern versions of prototype fix some of the goofy decisions they made in the past (they used to prototype built-ins which can break any and all other JS in use and had other poor design choices like gobbling up global reserved words with common webdev terminology) but they still seem to only lose ground to the newer kits.
There seems less stuff available but you should search around the CPAN a bit for other kits and see if there is something you can build on, e.g.: jQuery (jQuery is used/bundled in the lovely Devel::NYTProf) and ExtJs.
