Here you can find some usefull links !
My official retired 3D portfolio (seriously outdated): http://3drips.wix.com/portfolio
My (even older) deviantart page : http://griffon-nage.deviantart.com/
My sister portfolio (she is a very very good cartoon drawner !) : http://vertuchoux.carbonmade.com/
And her deviant page : http://vertuchou.deviantart.com/
Websites with good material references. Some have a random gallery browsing with a timer, so you can sketch like in art class :
Help for lighting :
Turnable models for 3D ref :