LGA 1155 with 3 PCIE Slots

Asus Sabertooth Z77
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Asus P8Z77-V PRO
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Are there any motherboards which offer x16 x16 x16 or x8 x8 x8?

You have a couple choices if those are for SLI:
PCIe 3.0 = IB CPU + Z77 LGA 1155 + (GTX 600 or AMD 7000 series) + PLX Chipset
PCIe 2.0 = SB/IB CPU + P67 LGA 1155 + (Any PCIe 2.0~3.0 GPU) + NF200 Chipset

PCIe 3.0:
ASUS P8Z77-V PREMIUM
ASUS P8Z77 WS
ASRock Z77 Extreme9
EVGA Z77 FTW 151-IB-E699-KR
Gigabyte G1.Sniper 3

PCIe 2.0
ASUS P8P67 WS REVOLUTION

What are your oppinions on the ASRock Z68 Extreme4 and the Asrock Z68 Extreme7?

If you mean for your stated use, SB (K), and as a new purchase then neither.

The ASRock Z68 Extreme4 yields a higher than necessary vCore and the ASRock Z68 Extreme7 Gen3 does use the NF200 and will work fine, but the ASUS P8P67 WS REVOLUTION would be my choice.

If someone starts out day 1 with 1 GPU I expect someday (2) two GPU's is a possibility -- so out of sheer habit I plan ahead in those situations GPU +1 (unless day 1 is 4-WAY).