There are no boards listed on Newegg that support what you want.
There are only 4 microATX boards listed with 2 PCIe x16 slots. 1 can't support dual-slot graphics, 2 more only have 2 DDR3 slots, and all four use AMD chipsets, so no SLI.
If newegg doesn't even list a compatible board, good luck finding one elsewhere. I think the sad fact is that Nvidia is slowly giving-up on motherboards in general. They can't make boards for Core i3,i5,i7 because of Intel's douchiness, and they probably don't care too much about AMD ever since they bought ATI (and because of their much smaller market-share and lack of a true enthusiast CPU). Therefore, the AM3/SLI niche market probably wasn't worth investing in.
You're only real option for microATX SLI is P55 and Core i5/i7.
I did a lot of searching before I settled on my MSI 890GXM-G65. I'd rather have SLI but I'll settle for maybe 1 GTX 460 running the graphics and 1 GTS 250 running PhysX until I build my next rig. If you really want SLI you're going to have to go with a full ATX board.