You can bring frags to sell, swap and donation to MR. Also bring cash and/or a credit card as there will be plenty of vendors from which you can buy all kinds of livestock and dry goods. You could also just come and enjoy the many speakers, speak with members about the hobby and put faces to the names on the board.
I suggest you look at the posts in the Fall Frag Swap 2008 forum, that way you'll get a feel for what goes on at the swaps.
So can you trade/sell your extra frags too?