There are a lot of information available about agile on the web. There are of course the obvious sites such as Agile alliance and Agile Manifesto. I have collected a few other resources with good information about agile work practices:

Simon Baker has written Agile Zealot’s Handbook

Joe Little has written an book(73 pages) about how he views Agile called Elements of Agile Style.

Kitty Hawk Consulting has a list of Agile/Lean resources with links to book and web sites.

Mishkin Berteig and Garry Berteig have written a good article about how agile work practices can be applied to non-software areas.

Deborah Hartmann agile reading list is also a good source of information.

Mishkin Berteig has posted Agile Benefits: Five Essential Reasons to Try Agile that really explains the good things with the agile work practices.