PLAYBILL EDU - I just discovered this and thought I should share. Great resource for those planning college for an arts career.
PLAYBILL - Playbill is a great resource for keeping up with Broadway News and finding Auditions and other jobs in the arts. FREE casting notices.
BACKSTAGE - This is a subscription site. You can browse for free to a point. But when you are ready to be a working actor, join and go audition every week. Daily when possible. Finding work as an actor is not that different than any other job. You have to leave the house and go interview - we just do it with monologues and songs.
ACTORS ACCESS - Tons of paid film work. Eventually you need an agent, but you can find work in student films and non-union projects, Indy films and sometimes even get yourself cast on legit TV, Film and commercials. Free to browse. You have to pay to submit yourself. When serious, go ahead and pay for the annual breakdown submission service that allows you to submit w/o additional fees (usually $2/submission).