Does he have any particular skillsets he would like to utilise?
Thats one of the joys of self employment - the world is your oyster you can do anything you want really. Even artists sometimes earn some money

Thinking of the tasks I have had in the last week where I would have liked to have had somebody else to do the job:-
Gardening, cleaning, painting, transporting goods, a mechanic that would do home visits, website content writing, webpage designer, ebay listing and email management, taking orders for campsite, answering phone, washing/laundry for rentals and changeover, farm hand, farm - 'baby'sitting, treefelling, woodcutting.
The best one I think is get into felling and selling wood - Its quite a saturated market and there is a bit more to managing trees than just cutting them down - but there is always going to be a cll for wood to burn and with the price of fuel, the amount of people now using wood is increasing. Depending on where you live it would also be easy to target new customers by looking at their chimneys

Some people also have limited space for wood storage so you could have a monthly delivery service? Dunno - my brother has just started selling wood as a sideline to his tree surgery and it seems to be going well as he get alot of the wood as a byproduct of his service. Target campsites or the like during the summer where people still have evening fires even if the weather is warm or just get on with stockpiling and seasoning your winter wood supplies. All you need is space to store wood and a supply thats cheaper thn your retail value.
Dunno really just an idea off the top of my head.
Baz