Be a due process server and deliver court documents to respondents. Everyone is suing or getting divorced nowadays, so the demand is there.

Heck, you don't even need a car. I started the business in an afternoon and made deliveries on my bike. Other deliveries I had someone else do (gave him half - I did nothing but take the order and pass it off to him).

Get a simple three page website and some business cards made up and you will make your 20G.

One bit of advice: Get paid in advance, every time. Even if it's a legal firm. ESPECIALLY if it's a legal firm.