"Web Therapy" (Showtime, Tuesdays). Lisa Kudrow's Skype-framed talking-heads comedy, which began on the Web in 2008, embarks upon its third Showtime season this week. Created by Kudrow -- who plays online therapist Fiona Wallice, a character as far from Phoebe Buffay as might be imagined -- with Don Roos, who directs, and Dan Bucatinsky, who plays Fiona's assistant, it's a testament to what can be made from a low-overhead idea in able hands. There is a coherent ongoing narrative (crafted by the three creators, and improvised upon by the actors) that this year finds a manuscript Fiona has written being turned into a Broadway musical, while her mother -- played by Lily Tomlin, born to splash around in this pool -- is setting up a rival service, Net Therapy. The new season will include appearances by Steve Carell, Billy Crystal, Chelsea Handler, Megan Mullally, Sara Gilbert, Meg Ryan and Matt LeBlanc, who appears as an online gambling addict, bringing to three the number of "Friends" co-stars that have appeared on Kudrow's show. (It's up to you now, Matthew Perry, Jennifer Aniston.) There is a sense of celebrity playtime (a growing modality in modern comedy) that recalls Alexandra Wentworth's "Head Case" or, for that matter, "Dr. Katz, Professional Therapist," though in those shrink-coms the celebrities played themselves (or "themselves"). As Fiona, more distracted by her own problems than interested in those of her clients (or friends or relatives), Kudrow draws herself up and inward, pinching herself into a sort of tower of haughteur -- with whom we nevertheless sympathize: Those people are crazy.