While searching for ideas to limit how many characters an HTML textarea could accept using Javascript, I found Snipplr, a service that reminds me how easy to use is del.icio.us. By the way, the del.icio.us guys are working on a new platform and trying (is possible?) to improve their UI.

Snippler allows you to save, search and tag those small pieces of code that we use so many times in our projects, snippets.

I know this may not be the first site doing it but it helped me and possibly would help you. Worth taking a look.