A few links that might be of interest to you:

WordPlay Publications , publisher of the book "Maxon's Poe", display and sell original artwork by Maxon Crumb. CrumbProducts sell signed prints, books and more by the whole Crumb family, including Maxon. A very nice fan page with a lot of rare Maxon Crumb artwork is Beatup.com. More scans of Maxon's pictures can be found in the Maxon Crumb Gallery of Another Robert Crumb Page as well as information on the Crumb Family Comics, a book edited by Maxon Crumb. Bill Delaney's Place features scans of Maxon Crumb's artwork, too, as well as a photograph of Maxon.

Of course there are many more Crumb pages on the net, most of them dedicated to Maxon's famous brother, Robert Crumb. Try Looking for Crumb? for its huge and up-to-date collection of links and lots of scanned pictures, Uncle Carl's R. Crumb Pages for the latest Crumb info, and Another Robert Crumb Page for artwork galleries, book reviews, a Crumb forum etc.