How many bikes are...
 

-Single speed
-Disc brakes
-Front suspension
-Fender/rack compatible

There should be a great many if your okay with a flat bar. I'd ditch the front suspension for commuting though.

125 the last time I looked

There are many, many bikes that fit your description. A personal favorite is the Niner One9. There are alternatives like the cannondale badboy range and similar offerings from marin, etc.

http://www.ninerbikes.com/one9.html
http://www.mtbr.com/reviews/29er/product_125403.shtml

There're also almost any of the Nicloai hardtails (available with rohloff, derailleur or single speed fittings).

http://www.nicolai.net/products/e-frames.html

I see lots of online pix of surly karate monkeys and 1x1s set up that way (1 spd, disc, even susp fork).