Music writer Irwin Chusid takes the reader on a tour of the somewhat fuzzily-defined world of outsider music. If you read the excellent WFMU Blog you've probably encountered Chusid's articles before, and he's no less entertaining in print than online. This was written in 2000, so it's now somewhat out of date -- Syd Barrett's died, Jandek's started performing live, and William Shatner's released another album, for example -- but it's an excellent overview of the field, and a bit of link-chasing from Chusid's web site will provide more detail for those you're interested. Recommended.
ISBN 1901447111.