I bought the 2008 Air Adventurer set as well, I love that tent. I also bought the 2007 Fight for Survival set. It was expensive but I bought the boxed set, extra figure and dogs as well. It makes for a really awesome display.
I picked up the Walmart AT figures when they were out as well as the Hot Topic Land Adventurer they put out the year before that. My Walmart never carried the 45th military figures or accessory sets which was too bad, I'd have packed up a couple of them.
The 12" Club membership figures are what drew me in back in 2002 and I've gotten them ever since. I've also picked up the accessory sets for them and have bought all the exclusive AT figures except the first one, the Land Adventurer. Oh, and I haven't bought the talking Astronaut but I probably should.
The 40th Anniversary sets were fun, I bought some but nowhere near the full range. I've actually liked the 40th Action Man sets a little better, more of a variety. I picked up two of the Mountaineer sets and the Jungle Explorer and have a Blues and Royals dress outfit on the way along with the SAS Parachute Attack set. That's been a lot of fun.