Depends what you're after out of it.
If you want to get some flying, try advertising something like "I'll wash your aeroplane in exchange for being taken flying" on the club notice board.
If you want to get to know shedloads more about flying machines, try volunteering at the nearest museum.
If you want to feel you've used some aviation skills and knowledge to make the world a better place, try contacting somebody like
Aviation Without Borders to see if you can help out.
G