And I chose it due to the SLI support, great reviews and SSD cache feature (however after reading many reviews and threads around TOMs, if and when I get an SSD ill use it as a dedicated drive, not as a cache). I also liked the idea of the Z68 having on-board graphics, just in case I ever ran into any problems with my GPU. The price difference between Z68 and P67 was so minor, it was worth the few extra ££ for the extra features a Z68 offers.
Gigabyte offers some slightly cheaper alternatives at a slightly lower price, but again nothing major and i'm really pleased with my ASUS board so its all good
60GB is plenty to use an SSD as a boot drive and have a few desktop applications (web browser ect in particular) just for that extra speed and quicker boot times.
Well over-all you've got a nice balanced mid-range build.
You could - if you wanted to save money;
Get a non-SLI ready motherboard (still socket p67/z68)
Get a good 500w PSU (enough for a single card).
Stick with an SLI ready motherboard and still get a 500w PSU (would mean grabbing a new PSU if you ever wanted to SLI though).
You could also get a cheaper SSD, i think the Crucial M4 comes up a fair bit cheaper than the Corsair Force GT.
Checking prices for the GTX 560Ti might not be a bad option either, it performs at a very very similar level to the 6950 (practically equal) so if one is selling for cheaper than the other, its probably worthwhile.
Another very minor money saving tweak would be getting 4GB RAM over 8GB (still the same 1600MHz CL9 spec though).
You could also buy a cheaper case. Full tower isn't necessary. Any mid-tower ATX should be fine for your build - and would cost about half the one you listed costs.
Some really good ideas in that build, the mother board especially looks like a good compromise between the pro and extreme4. The OCZ's are quite a bit cheaper than other ssds but they get a few complaints; what's your experience been with them?