My favourite modelling application: It's powerful, it's easy to use, it's stable and it's free!
For tutorials, look on the front page and in the forum
Very inspiring modelling work.
The head modelling tutorials at this site is the best I know.
A big graphics forum. The wings forum is great! The poser forum is the biggest one in existence, there is much garbage going on there, but every useful information about Poser will come up there, eventually.
I mainly visit because of the Poser 5 forum. It has a much better signal to noise ratio than Renderosity.
Very useful site for Poser 5 users. Check out the Firefly FAQ!