A FlyerTalk regular, Dorian, has created a site...
http://www.informationlab.com/rtw.htm

...that contains details of *A RTW tickets, prices (depending on country of origin) and basic rules. When planning my *A RTW ticket I used a Travel Agent in the UK as dealing with the airlines was impossible. Airline ticket staff don't seem to be unsure (or unwilling to spend the time) of how to build a complex trip.

My agent has been excellent and has pressurised the airlines into releasing the appropriate booking class if no availability was showing for a particular flight.

Details of my itinerary can be found at:-
http://www.flyertalk.com/forum/Forum82/HTML/000164.html