This travel page has links for the adventure traveller.
 The general outline of an adventure tour:

1/ small less intrusive groups (10 - 20 people) 
2/ use small locally owned guest houses, inns, camps ... 
3/ one tour leader to organize accomodation and transport
4/ explore with city walks, rural treks, local buses, taxis, minivans 
5/ use local tour guides from the area
6/ general travel schedule with lots of free time to explore
7/ single travellers share rooms with no single supplement
8/ mixture of people from the UK, Australia, USA, Canada and others
9/ most adventure tour companies are UK or Australian based