Cobweb's bi. She's got that thing with Greyshirt, among others.
As for lesbian heroines, the Big Two've got Renee Montoya, Kate Kane, Anissa Pierce, Xi'an Coy Manh and Phyla-Vell. (Though Anissa might be bi; she's never been explicitly stated to be a lesbian.)
Oh, and Babs Gordon, but she's still in the closet.