BusinessMarketing & Resources are definitely your best ones. They are a little long, but as .US names start getting bought up, these will get more valuable.
Great keyword bids on BusinessMarketing ($5.28), good ones on BusinessResources too ($2.22). Do you get any traffic?
I would definitely say hang on to them. Undeveloped I would say a few hundred a piece. If you develop them, obviously more.
Just my 2 cents. Good luck with them.