Hey brownemily--
Does your undergrad have a reference service? I was able to use mine and found it very helpful, even though I graduated over a year ago. With a reference service, you get your reference-writers to send an LOR to the service (not the schools you're applying to), and then once all your letters come in they send out all the letters in one big packet. It makes everyone happy-- reduces your stress level, your recommenders only have to send one letter one place (instead of to each seperate school), and the schools get the letters as one packet instead of individually, which has to be easier to keep track of.
If a reference service isn't an option, I would give each recommender a stack of stamped envelopes with the addresses of all the schools you're applying to. I would not forward them myself b/c you're supposed to waive your right to view the letter. Also remember that if your undergrad has a premed committee, you are supposed to send a committee letter. My undergrad doesn't have a committee, so I can't help you there.
good luck and i hope this helps!!