How much do you want to spend? Makes a big difference.
You could go with something like this - GIGABYTE G1.Assassin LGA 1366 Intel X58 SATA 6Gb/s USB 3.0 XL ATX Intel Motherboard. About $250 new here (http://www.newegg.com/Product/Product.aspx?Item=N82E168...). It will let you take advantage of 2 pcie 2.0 X 16 plus the usb 3.0 slots and connectors. Just make sure your case is big enough.
If you'd rather - you could change to the newer Z77 chipsets (socket 1155) with the pcie 3.0 lanes and the availability of more memory. A board like this ASUS P8Z77-V LK LGA 1155 Intel Z77 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS for only $150 at newegg. And then you would need a new cpu - I would recommend one of the newer Ivy Bridge, something like this Intel Core i5-3570K Ivy Bridge 3.4GHz (3.8GHz Turbo) LGA 1155 77W Quad-Core Desktop Processor Intel HD Graphics 4000 BX80637I53570K. Or if you want more cores you could go with this much cooler Intel Core i7-3770 Ivy Bridge 3.4GHz (3.9GHz Turbo) LGA 1155 77W Quad-Core Desktop Processor Intel HD Graphics 4000 BX80637I73770. Give us a price and we'll see what we can help you with.