One of the funnest parts of Yuletide can be getting matched on that one fandom you love that none of your friends are familiar with, so you might find yourself in need of a different beta than usual! Or they tell me this is one of the funnest parts, anyway ;)
This post will serve as a place-holder for anyone interested in offering beta services. You do not have to be a Yuletide participant! You can offer fandom-specific betas, and/or general technical betas.
And if one of the participants feels they really need a fandom knowledgeable beta, and they can't find one here, IRC is a good place to start.
This link contains instructions on how to get into the #yuletide chat room on the server we use. Once you are there, you will see people with the word "hippo" in their name. You can private message one of these folks and they'll announce in the chat room that a beta is needed for [fandom], check back with you to make sure anyone volunteering isn't your recipient, and then have the beta message you.
(ETA:
shusu has more info about IRC and hippos at
http://community.livejournal.com/yuletide/757383.html)
If all else fails you can write to
yuletide@yuletidetreasure.org, and we will see if anyone else offered that fandom and is willing to serve as a beta. Please use this service sparingly! And consider that the people we will be contacting are also working on Yuletide stories; you probably won't want to wait until the very last minute to contact them, or to get your story to them.