From Kotobukiya, Harley Quinn Bishoujo Figure Unmasked. You may have seen their other Harley Quinn bishoujo statue but this one is unmasked and without her jester hood.
From JUN Planning, Supergirl Pullip! I wasn't able to verify if this was a SDCC exclusive but if their previous showings at SDCC are any indication, she'll likely be for sale beginning at the show.
From Mattel, 1960s Catwoman Barbie. It's been stated she isn't exclusive to the show, but she will be available beginning at SDCC. Batman also available.
Also from Mattel, Webarella Monster High Doll. Who is already SOLD OUT via pre-sale. Very Spider-Man inspired, no?
From Hasbro, Glitter and Gold Jem doll with accessories.
Lastly from artist J Scott Campbell and colorist Edgar Delgado and Marvel Comics, a special variant cover for Uncanny X-MEN, "cosplay edition".
You can check out a full list of all the SDCC 2013 exclusives on Awesome Toy Blog. Is there anything you know you'll be getting in line for at Comic Con?