good books/sites for Regex

Hi,

Regex is something i'm using more and more, but can never seem to get the syntax right. the syntax looks spot on but doesn't do what i want or in the order i want it. does anyone know of any good sites or books to teach myself.

It would be good to have a tutorial-based one where i can have a go, get it right then move on (it's how i personally learn best)