at work, we build lots of custom applications for specific classes or professors. this means that most of our stuff isn't very generalizable and gets locked up in the ivory tower, which is a shame since we do (IMHO) good work. every once in a while though, something comes along that is a little more general purpose that other people might find useful.
lately, i've been on a kick of building small, self-contained web applications that are designed to be mixed and matched and used to build larger applications. exactly the kind of thing that Ian Bicking wrote about.
my most recent mini-application, and one that's made it out of the ivory tower, is called Tasty and is a tagging engine. probably the easiest way to think of it is as del.icio.us but designed to be embedded inside an application. it supports a very rich tagging model (basically what's explained on tagschema.com) and is very efficient.
also, fwiw, Tasty has been powering the tagging on thraxil.org for a few weeks now (it was sort of my sanity check to make sure that the API wasn't too obnoxious to integrate into an existing architecture and to make sure it performed ok on a reasonably large set of tags).
(update: Ian Bicking has an interesting followup that gets more into the small applications vs frameworks/libraries discussion and even posits an approach to making integration between python applications even easier)