Is there an easy way to trim the ends off green beans quickly?
I have found that scissors is the answer to this particular problem. Simply grab a few bean, snip the ends and then turn the hand over and snip again.  This doesn't wield beans that are uniform in length though, so if you need that, you will still have to do some cutting. I would say that you could blow through a batch of five pounds in a few minutes once you get the rhythm. 

P.S. I say scissors but what I really use is tin snips a la Alton Brown.