Here's the IGN site with a bunch of the Easter Eggs in the game. I forgot about the Halo poster easter egg on Ord Mantell and the Holiday Special drink you can get on Alderaan.
There's also a protocol droid you encounter on one of the Dromund Kaas missions at Lord Grathans Estates. His name is PO-12 and he's actually voiced by Anthony Daniels. When you're speaking to him, he mentions that he's 'fluent in over 100 forms of communication and dialects.' An obvious nod to the "fluent in over six million forms of communication" that C-3PO always boasts.