Obviously, getting rid of stuff in your room and making some money back is always awesome. That's why I've been attending swap meet for the last few years. However, if you still have a bunch of manga you don't want and can't sell off by Fanime 2013, there's an awesome way to lighten your load.
There was a new... "event" I guess it could be called, this year: the Manga Lounge! Basically, an at-con library featuring nothing but manga! There was a decent collection to start with, considering this was its first year, and it can only get better. The lounge is accepting donations of any unwanted manga, regardless of its age, genre or language! That's where you come along. Make some space in your room and help others get an opportunity to experience and enjoy a medium that makes up a huge part of Fanime - bring in your unwanted manga, and see it become a part of the library for future cons-goers to enjoy!
They will be open Monday morning in the Hilton if you're around, and with any luck, they'll be back next year as well. All you have to do is bring the manga in and drop it off - the lounge staff will see that it gets sorted and put up right away. And while you're there, you can pick up and read other titles that you may not have come across before. Unfortunately, they aren't able to purchase any manga off you, but anything you'd be willing to part with would definitely be appreciated, I'm sure.