Survivor Theme Birthday Party!!!

I've decided to go all out this year for Dave's 30th birthday. Technically, his birthday has come and pass without much of a bang (actually, not even a crackle), so I've decided to make it up to him in a big way. I'm going to throw him a belated birthday party while we are in Idaho this August. It's going to be a Survivor theme party where we split the guests up into tribes and challenge each other to outplay, outsmart, and outlast the other team... or however that saying goes. I've come up with some pretty rad games, but could use a few more ideas if anyone has any to give.

Some ideas:
1. Fire Challenge -- make a fire with flint/steel and build it up enough to burn through the rope strung about 2 or so feet off the ground.
2. Spear Throwing Contest -- every person on the teams get 3 throws. Throws are worth points based on where the spear lands. The team with the most points wins the challenge.
3. Scavenger Hunt -- players search for puzzle pieces through clues/riddles. Once all of the puzzle pieces have been retrieved, the team goes to their assigned table and begins assembling. The completed puzzle will give the team the last clue needed to find the challenge prize... or some sort of version played off of that.
4. Worm Eating Challenge -- teams compete to see who can chew and swallow their gummy worms the quickest. I thought about making it some gross food like rice with some outrageously hot, hot sauce, but decided that I don't want to be responsible for any myocardial infarctions. Old people and hot stuff... they no likey!!!

We'll have a giant slip n' slide at the party, too, so I would like to come up with a fun challenge to use that one in. I'm thinking 5 or so games should be plenty and it needs to be geared more toward adults, although there will be some teenagers participating as well. I'm going to have easy, fun games for the little kids so that they can keep themselves entertained while the big kids have their fun in the sun.

Man, if I can pull this off then I should be considered wife of the century... year?...month?... okay, day!!! So, suggestions? Anyone? Anyone? Buehler? Buehler?