I am in the process of wrapping up the most complex WordPress plugin that I’ve ever made.  Its a work-related project for Dealer.com in Burlington, VT so I can’t blow the lid off it yet, but its looking pretty sweet and should have a number of sweet applications.   I learned a ton about extending the functionality of WordPress, especially integration with external databases.  Drop me a line if you’re trying to stretch WordPress beyond its normal bounds, maybe we can whip something up.