Art Crime:
For the FBI Art Squad and their list of the Top Ten Art Crimes:
http://www.fbi.gov/hq/cid/arttheft/arttheft.htm
And Interpol’s art site, with their own Most Wanted:
http://www.interpol.int/Public/WorkOfArt/Default.asp
For updates on thefts, forgery, and antiquities trade, plus plenty of resources regarding forgery and theft, the Museum Security network can't be beat:
www.museum-security.org/
More general information about art-related goings-on:
http://www.theartnewspaper.com/

Forgers:
Han Van Megeeren
Imprisoned and accused of selling a Vermeer to Goering under Hitler's reign “which amounted to treason” Van Megeeren produced an exquisite forgery while in jail to prove that he had sold Goering one of his own copies. The charges were commuted to forgery. 
http://www.mystudios.com/gallery/han/index.html

Elmyr de Hory
A prolific and versatile forger, de Hory claims that ninety percent of his fakes have gone undetected and hang on museum walls.
http://www.crimelibrary.com/criminal_mind/scams/elmyr_de_hory/index.html

John Drew
Drew was imprisoned for commissioning fakes from artist John Myatt (see below), and then forging documentary “Proof of provenance”. He slipped the papers into art library collections for investigators to find while researching the forged works of art.
http://www.nytimes.com/library/magazine/home/19990718mag-art-forger.html

John Myatt
Prolific forger in a profitable partnership with art dealer, John Drew. http://news.bbc.co.uk/hi/english/uk/newsid_279000/279937.stm
http://www.nytimes.com/library/magazine/home/19990718mag-art-forger.html
 
Eric Hebborn
Murdered on the streets of Rome in 1996, Hebborn was a prolific forger who reveled in making fun of the legitimate “art experts”? He is author of The Art Forger's Handbook.
http://www.time.com/time/magazine/1997/int/970310/aart.the_artful.html

Tom Keating
A real character, this cockney house painter was imprisoned for fraud when he tried to pass off 13 drawings of his as the work of British painter Samuel Palmer. He later confessed to having painted 2,000 “Sexton Blakes” (fakes).
http://www.smh.com.au/news/9807/18/features/features2.html
 
Interesting Art Sites:
Research, price and find antiquities and art
http://www.artfact.com
Michel Van Rijn is a very interesting character in the world of art, art forgery, and art smuggling.
www.michelvanrijn.nl/
History of Pigments in Art:
http://www.multimediaarts.com/watercolors/colrhist.htm
Lots of information about art crimes, forensic art, illegal antiquities trade:
http://www.yourbrushwiththelaw.com/index.htm

Resources for mystery fans and writers:
Mystery Writers of America:
http://www.mysterywriters.org/index.htm
Sisters in Crime
A fabulous, supportive group of readers, writers, and published authors of mystery:
http://www.sistersincrime.org/
Crime scene investigations—lots of nitty-gritty information:
http://www.feinc.net/cs-inv-p.htm
Mystery writers’ resources:
http://www.zott.com/mysforum/links.htm
A great list of book groups:
http://www.mysteryreaders.org/groups.html
Mystery bookstores—support your independent booksellers!
http://www.mysteryreaders.org/bookstores.html
http://www.mysterybooksellers.com/