other singers like Patricia Barber.....

Holly Cole. She has Jane Monheit's technical skills with Patricia Barber's dark, powerful interpretation. Good stuff. Start with Temptation (all Tom Waits covers).

If you want to explore an unknown novelty, bordering on off topic, try Bet Williams at http://www.epiphanyrecords.com/. She's more a kind of arty singer songwriter than jazz/torch song singer, and I can't vouch for the recording quality, but you could check out some mp3s at the site. I would tend towards "Epiphany Project" (Bet Williams & John Hodian) than the album with "Ooh La La". That latter song is not my cup of tea. Try "Lockerbie" and "Long Gray Line".

I agree with the others who mentioned "Dave's True Story." That is one hell of a combo. And to make it better, they are a little twisted (e.g., the title of one CD is "Sex Without Bodies").

Wait till you hear Jane Monheit's DVD "live at the rainbow room".

If you don't mind the Norwegian language: try Kari Bremnes.