Maybe I could get someone famous in the dive/conservation society to come and do a live chat.
Sounds like a great idea if you can.
The other thing I have seen/ done on other forums it youtube style interviews with well know people using questions off the forum. This allows for time differences and allows new people to look back.
Charities may be good for them to do some publicity work and some companies will do talks (I know poseidon have been doing some talks on re-breathers).
But it's all about getting the commitment from the people to do these things.