Here are some pics of the first single-speed bike that I built. I just put the finishing touches on it a couple of days ago. It's a sweet ride, geared perfectly for riding the hills in SLO.
BEFORE: Huffy "Savanna" *** $30.00 on Craigslist

AFTER: Total Cost $130.00
I stripped off all the components and started over with just the frame. Originally I was going to paint it Propane Tank White, but after a couple of days I got attached to the Metallic Blue. I used a freewheel BMX cog and the chain ring off of my old Schwinn from when I was a kid. The ratio is 40:16. I flopped and chopped some old road bars to make custom Pursuit Bars. Other components include: vintage NOS saddle; vintage Redline BMX platform pedals; SR stem; bitchin' Huffy brake lever; old school Schwinn calipers; Araya 27 x 1 1/4 wheels; Duro red-wall tires.