I don't watch Lost, but I do realize how big a deal it is to be on that show because I know people who've been on it.
Josh Randall had a key role in one episode (Season 2, Episode 7: "The Other 48 Days"), and he told me he gets stopped at airports so that fanboys can school him on how he fits into the mythology of the series. (Nerds!)
Now Leslie Ishii, who writes plays in my playwriting classes, just popped up as "Lara Chang" in the episode titled "Some Like It Hoth" (Season 5, Episode 13), and will appear again in Episode 15 on May 6, 2009. It's a role that has already yielded her her own page on Lostpedia, a wiki site. (Nerds!)
She's detailing her on-the-set adventures on her new blog: check it out. (Nerds!)