The Halo HG splined Fix-G hub has been out for a fair while now and everyone who has one loves it, fact. All you lovers can now swap your 3/32” cog for an 1/8” Fat Foot cog because they are now available from 12t right the way up to 20t. Your LBS will probably be able to order one in for you, if not then try Charlie the Bikemonger.
The Fix-G hubs come in 3 different configurations: double Fix-G; Fix-G/fixed and Fix-G/freewheel. I will be posting a review of them very very soon.