There's a new girl in town ... Well, sort of. Dan Finnerty, 30, is the self-proclaimed straight guy who sings songs by women (like Linda Lavin's theme to TV's Alice), and his Dan Band is one of the hottest tickets in Hollywood. ''It started off as a joke,'' he admits about the cover-song fest. ''I thought singing 'I Am Woman' at karaoke was funny, then it just kept growing.'' In addition to rocking as the house musicians on Oxygen's Pajama Party, the Dan Band send up such ditties as Christina Aguilera's ''Genie in a Bottle'' and Wilson Phillips' ''Hold On'' at West Hollywood's Largo nightclub where Brad Pitt, Jennifer Aniston, and Helen Hunt have all turned up to watch. ''I'm obsessed with the Dan Band,'' says fan Laura Dern. ''In fact, I'm stalking them. It's the best thing I've ever seen in my life, and I'll go to every show they ever have.'' Finnerty goes wide with a cover of ''A Groovy Kind of Love'' on the soundtrack of Jennifer Lopez's The Wedding Planner, in which he also has a cameo. How does the crooner who's married to Kathy Najimy like his star-studded audiences? ''Gloria Steinem came to a show and walked in during 'Gloria,''' he beams. ''You can't pray for that kind of s---!''