Regex

Syntax - re2 - I define UNIX as “30 definitions of regular expressions living under one roof.” —Don Knuth - Project Hosting on Google Code

http://code.google.com/p/re2/wiki/Syntax list of syntax supported by new regexp lib from google

I Knew How To Validate An Email Address Until I Read The RFC

http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx notes about testing for valid email addr syntax