http://www.zotacusa.com/products/mot...form_factor=27
That's the page you need to look at for making a gaming itx rig, though for a rig with some serious oomph you'd be looking at...
This (Zotac)
This (ASRock)
This (Asus)
This (MSI)
This (Gigabyte)
And soon, this (EVGA)
I believe the ASRock is looked upon the most favourably of all of them, though the EVGA might give it a run for it's money if it's not too expensive.