First thing to understand is that Sandy Bridge processors have 16 lanes of PCI-E 2.0, so a pair of graphics cards will run at 8x each rather than 16x. If you need maximum performance and have the money, Z77 boards with PLX chips can give you the functional equivalent to 16x/16x (but uses quite a bit more power).
That aside, most H67/H77/Z68/Z77 microATX or larger boards will support two graphics cards. The cards themselves depend on what models you are interested in, since some companies are better at one brand than another. In general though, make sure the board supports the spacing size you need, usually 2 slots between cards.