Here is a list of sites offering free graphics to help you kick start your own projects.
I try to limit this list to completely free graphics ( free for personal and commercial, no attribution necessary !)
For sites that contain premium items, I link directly to their freebie page.
free vintage vectors - Recently changed their domain and is a bit slow, but a great source for vintage vectors
[NEW]RetroVectors - Recently found this! Nice fast loading site filled with retro and vintage vectors
All Silhouettes - Find vector silhouettes for everything under the sun and more
graphicloot - Has some great freebies but not a 100% sure with the licensing, but looks to be completely free.