a barebone kit is almost a complete pc
depending on the kit you would have little to add to it
look here for all of your options: (amd or intel, NVIDIA or ATI)
http://www.tigerdirect.com/applications/category/category_tlc.asp?CatId=31&name=Barebone-Kits
here are some examples:
here is an Intel and NVIDIA one
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3984221&CatId=2405
EVGA nForce 680i SLI Socket 775 Barebone Kit - Intel Core 2 Quad Q6700 2.66GHz OEM, 512MB PCIe 2.0 Card, 500GB SATA HD, 4GB DDR2 PC6400, ATX Full-Tower Case, 650 Watt Power Supply
here is a more expensive one
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3837301&CatId=2405
EVGA nForce 780i SLI Socket 775 Barebone Kit - Intel Core 2 Quad Q6700 2.66GHz OEM, 512MB PCIe 2.0, 500GB SATA HD, 20x DVD±RW, 2GB DDR2 PC6400, ATX Mid-Tower Case, Clear Side, 1000 Watt Power Supply
here ia an amd
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3775001&CatId=2626
Visionman BBA-377X00 AMD Gaming Barebones - AMD X4 Phenom 9850 Black Edition / MSI K9A2 Platinum / 4x Crossfire / 2GB DDR2-1066 / Flash Reader / Gigabit & Wireless LAN / NO Video / 850 Watt
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3747050&CatId=2626
Intel DX38BT Socket 775 Barebone Kit - Intel Core 2 Quad Q6700 2.66GHz OEM, 2GB DDR3 PC10600, ATX Mid-Tower Case, 600 Watt Power Supply
there are some examples from tigerdirect.com
you could look up some more from newegg.com if you wanted to
but i really dont like there offerings
thats just me though