Something that people either aren't aware of or have forgotten... the option of in-house training by the resident experts is a powerful tool that's frequently over looked. It also builds "esprit de corps" and also helps the resident experts because you do have to know your stuff to teach it.

I used Lunch'n'Learns a lot in the last couple of companies. You'll be amazed at the kind of performance you can get out of people for the price of a couple of pizzas, some soda, and a nice salad. It's real good practice for those making the presentations and it looks awesome on a resume, as well.