The old song goes "the best things in life are free".. and the same goes for bikes.
I have had two bikes which I found in the dumpster (rubbish bin here in Australia). With some time and elbow grease, and sometimes a little bit of money you can restore a bike which was destined for the dump into something that is fast and fun to ride around.
This instructible shows you how to restore a dumpster bike – in this case a 10-speed road/touring bike. These bikes are commonly thrown out, can be converted into a single speed or easily renovated into a working bike.
I have concentrated mainly on providing the resources and hints, rather than the in-depth detail for each section of the bike. The reason for this is that no two bikes are the same and if I go into too much detail for one part (eg. the headset).