The Victorian explorer Sir Richard Burton is an example of an adventurer who was born too late. He was a gifted linguist and expert swordsman, travelling through some of the last areas on Earth that Westerners hadn't explored (and took a spear in the face for it one day, but escaped with a scar and four fewer teeth). He even went on the pilgrimage to Mecca, which would have meant his death if he had been discovered.
http://en.wikipedia.org/wiki/Richard_Francis_Burton

Been reading the World Collector?

No, I first heard of Burton in Farmer's "Riverworld" series. I'll have to look it up: http://www.amazon.com/Collector-Worlds-Richard-Francis-Burton/dp/0061351938/ref=sr_1_1?ie=UTF8&s=books&qid=1249271660&sr=1-1

You answered your own question when you said an Adventurer could be anybody, many times specific types of people, soldiers, archeologists, traders, sailors...basically anyone willing to "adventure"

I would agree and say that Richard Francis Burton is probably the epitome of the modern adventurer, basically a lecherous academic with military training.