In reply to Captain Gear: Have a look at comapnies specialising in RTW (round the world) flights. SCA is a start but there are cheaper.
The price varies on stop-overs, but was about £1000 for 4 stops when I last looked (a while ago now though!).
A general search of RTW and Gap Year flights should set you in the right direction.
Also, if you want travel insurance, woth looking at backpackers insurance as this is cheaper for long trips/multi-stop travel.
Hope that helps, enjoy!