Fixed Super Light Super Safe

Just get an alu sprocket. I have a alu 17t and its lasted far longer than I expected.
http://urbanvelo.org/velosolo-aluminum-track-cog/

Just get a 15T, together with a 40 tooth chainring.

If you plan to go with deepish rims, get the non-cutout chain ring. Simples.
Good idea on the alu

But 40/15 is only 3 skid patches :-(

I got an email back from Fibrelite and they say that they can only do 38T on a 130 BCD annoyingly.

non cut out?! You mean *gain *2 or 3 grams?! Furry, I am disappoint!