Well folks, the cat's finally out of the bag ... and its name is WICK.
Are you familiar with GMail's cool auto-completion from its Address Book when composing an e-mail? Other web-based e-mail systems such as mail.yahoo.com have tried to duplicate this functionality without quite reaching parity in terms of features and cross-browser compatibility.
As most everybody else was likely too busy with a life beyond coding to bother tackling this challenge, I took it on last year, in the form of a standalone library that should be easy for any developer to include in their site or application. It's now mostly ready for consumption, open-source under a BSD License, and lives at sourceforge under the project name "wick": Web Input Completion Kit.
It needs much work and improvements to move beyond Address Book-related use cases. Which is where I'm hoping skills and enthusiasm from the Open-Source Community will help drive this project further along.