Ok, i've got a bunch.
Because we haven't had enough Sci-Fi in the past for my liking, I'm gonna start with some Sci-Fi guests. And aren't I nice, i'm even giving leads for how to get in touch with them.
Dwight "Reg Barclay" Schultz:
http://dwightschultzfansite.nl/ for the official fansite,
Orson Scott Card, author of Ender's Game, which has a movie coming out a week to the day before the con (March 15th, 2013)
http://www.hatrack.com/ is his official web site
Now for some voice actors:
Lisa Ortiz, voice actress from too many things to mention
http://www.lisaortiz.net/Related: Crispin Freeman, voice actor ALSO from too many things to mention
http://www.crispinfreeman.com/Get both and have a Slayers reunion =D
Webcomics:
Chris Hazleton, creator of Misfile
http://www.misfile.com/?menu=contact_us Kelly "Coelasquid" Turnbull, creator of "Manly Guys Doing Manly Things" as well as the show "Ugly Americans"
http://thepunchlineismachismo.com/castMusical guests:
Lindsey Stirling
http://www.youtube.com/watch?v=b3KUyPKb ... ure=relmfu is probably her best known work.
http://lindseystirlingviolin.com/ Arm Cannon
http://armcannon.com/