If I had to think of an actual physical adventure partner (as opposed to research skills and a Zen attitude), it would have to be my faithful Canon Powershot A80 camera.
My parents gave met this camera in 2003. I used it primarily for taking photos of my laboratory specimens for school (yuck) but since then, it’s been used to document my adventures both here and abroad.
I finally bit the bullet and sold my camera after buying a Canon S95 this February 2011. My oldie but goodie camera went to a good home though, and will document a different family’s adventures for many more years to come.