Agile Product Development
I wrote this article in December for Geek Guides. Though it's focus is on making systems engineering more agile, I think it's very applicable to any design process. Maybe bring A/B testing in during prototyping, or get more client feedback sooner. Whatever you're designing, the point of agile is that you've got to figure a way to test your design as early in the process as possible if you want to remove expensive rework later.
Anyway, here is is. I hope you enjoy. :)