Colonel Tigh: He’s hearing strange voices. While that’s not too surprising, considering he’s a complete drunk — could the Cylon’s have planted something in him while he was in captivity on New Caprica. For that matter, could Anders have the same problem? The only people who seem to hear strange voices were on New Caprica. That said, Tigh’s been through complete hell, having to kill his wife, losing his wife et al. There’s no way he’s a bloody Cylon.
Dr. Baltar: Too obvious (in spite of the fact that he’s seemingly evolved into BATTLESTAR’S version of ‘Jesus’). The writers of BSG would never spend three years building up the most complex and morally ambiguous character on television just to have his actions explained by the fact that he’s a Cylon.
President Roslin: In the world of television (and at times in real life — see Bush/Cheney), it’s never the person in power who’s the traitor, it’s the second in command. There’s no way Roslin is a Cylon, but her Chief-of-Staff Tori, well she’d be the ideal Cylon spy. Wouldn’t she?
Tori: How much do we really know about Tori? Aside from the fact that personal hygiene doesn’t seem to be her strong point and she has an almost scary single-white-female vibe around the President, not very much at all. Add to the list is last night’s observation by Roslin that she’s been acting awfully ‘strange’ lately. We may have a winner! and an ideal candidate to come out of the Cylon closet.
Lee Adama: Speaking of acting strange. Not only did Lee throw away his military career to defend an accused mass murderer, but he also seems to have some seriously secret abilities when it comes to designing clothes. Did you see that suit? Talk about ensuring his place on Galactica’s Best Dressed List 2007!
Sam Anders: Our final suspect. Anders being a Cylon would make sense. For one, he heard the music/voices that Tori and Tigh heard. But more importantly, with Starbuck ‘dead’, the writers need a reason to keep Anders around (as Ronald D Moore has mentioned on his BSG podcast that he’s a big fan of the actor who portrays Anders). Making him a Cylon would definitely give him an integral role to play in the fourth season.
So there they are, the unusual suspects. Post away with your guesses and assuming you’re right, be sure to check back next week to lord your BATTLESTAR GALACTICA genius over everybody else. (And as a courtesty to the rest of us, please don’t post spoilers if you do indeed know the outcome of next week’s season finale.) 
