Anyway, I'm about half-way through the second season, and I've noticed a distinct trend of guest appearances by well-known genre actors from other shows/movies. Linda Blair (from "The Exorcist") was one of the most notable (but least recognizable) examples. Amy Acker (most notably from "Angel"), Julie Benz (from "Buffy," "Angel," and "Dexter," among other things), Amber Benson (Tara on "Buffy"), and the actress who played "Six" on "Battlestar Galactica" were the ones I noticed most easily thus far. Apparently, in future episodes I will also see The Cigarette Smoking man from "The X-Files," Robert Englund (Freddy Krueger from the "Nightmare on Elm Street" movies), Kaylee from "Firefly," more Buffy folks (Spike, Cordelia, the Mayor, and Harmony), more "Battlestar" people (Baltar, Saul Tigh, and Helo), and various "Stargate" people (Daniel Carter, Samantha Carter, Major Hammond, Jonas, etc.) Also, Gary Cole (who I know from "Babylon 5" and "Crusade") and Callum Keith Rennie (who I remember most as Leoben on "Battlestar Galactica," but who has also been in a number of other shows I've watched).
It's like playing Name That Actor. It took me a while to place "Six," for example, because she looked so different. It's a fun game, though, to occupy me while I cough and/or try to prevent coughing.