For all things 3D:
www.3dbuzz.com --Free training and a wonderful community =D
www.cgtalk.com --Another great gathering of friendly cg people

...and now for the 2D:
www.conceptart.org --A perfect place to work on your drawing and painting skills

a bit of inspiration for you:
www.mstieber.com -- Mike is God (but then again, he told me to say that...)
www.planetsack.com --The Maya man himself....Jesse Rapczak
www.optidigit.com/stevens/ --Steven Stahlberg's amazing works
www.rustboy.com/ --Brian Taylor's short film in progress
www.lemenaide.fws1.com/index.html --the art of Myst artist Ron Lemen
www.tangrala.com/ --Katy Hargrove's extensive gallery
http://leigh.cgcommunity.com/ --Leigh van der Byl AKA: texturing goddess
http://www.waylonwinn.com/ -- Fist of God's awesome work!
http://creativevein.com/ -- Alex Velazquez just rocks...models, textures, concepts...
http://www.t3h-v.com/ -- Vitaliy Naymushin... another master character artist