Zed Shaw released an extensive Regex Tutorial online. I haven't read it yet, but since it's Zed my guess is it's really really good.

Josh Adams is a developer and architect with over eleven years of professional experience building production-quality software and managing projects. Josh is isotope|eleven's lead architect, and is responsible for overseeing architectural decisions and translating customer requirements into working software. Josh graduated from the University of Alabama at Birmingham (UAB) with Bachelor of Science degrees in both Mathematics and Philosophy. He also occasionally provides Technical Review for Apress Publishing, specifically regarding Arduino microprocessors. When he's not working, Josh enjoys spending time with his family. <a href="http://www.erlang-factory.com/conference/show/conference-6/home/"><img src="http://www.erlang-factory.com/static/upload/media/1389191028314604speaker120x125gif" alt="speaker badge" /></a>