San Diego Comic-Con is the ultimate comic book convention. This year it will be held from the 18th of July through the 21st. USA Today revealed these exclusive Lego minifigures just a few days ago. These four exclusive minifigs will be available only to Comic-Con attendees. This year Spider-Man and Spider-Woman from Marvel Comics will be available. While from DC Comics, Superman and Green Arrow will also have exclusives. These four figures will fit in perfectly with the Lego Super Heroes line.
If you can attend, make sure to pick these up. These usually run out pretty quickly. In previous years, the exclusive Lego minifigures have always become high priced collectors items.
Lego is also offering two exclusive sets at SDCC this year: http://legogenre.com/san-diego-comic-con-2013-lego-exclusives-micro-bag-end-star-wars-jek-14-starfighter/