http://www.digimods.co.uk
An excelent site about virtual tuning - tutorials, forum, galleries

http://www.photoshopchop.com/forum/
Photoshop Forum with car tuning section - Huge number of members

http://www.iacoski.com
Great site by a Polish guy - maybe the best PS tuning master on the scene

http://www.seriouswheels.com
Great resource page with hundreds of hi-res car pictures

http://www.garage-inc.tk/
My friends website - virtualy tuned american muscle cars

http://www.highresautoimages.com
Another great resource page - 1600x1200 images available

http://www.dieselstation.com/
My favourite resource page - for updates check the forums

http://www.forddesktops.com
All Ford hi-res pictures and wallpapers

http://www.desktopmachine.com
Huge car related wallpapers site