I did single speed for a while just to get my legs used to the gearing, then went fixed and haven't looked back. A few "oh cripes" moments to begin with, but you'll get used to it. I rode a freewheel for the first time in three years last week and it felt weird.
I know there's been some Kona bashing above, but if you can look past that (and an orange wheelset), this link will save you some dorra:
http://www.chainreactioncycles.com/Models.aspx?ModelID=80319&utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom
I did single speed for a while just to get my legs used to the gearing, then went fixed and haven't looked back. A few "oh cripes" moments to begin with, but you'll get used to it. I rode a freewheel for the first time in three years last week and it felt weird.