I've been a hunter all my life, but I've never gone after waterfowl (several species of ducks, plus canada geese are very common in my area).

Being an avid predator caller, I've always respected the skill required for waterfowl calling, and now I'd like to pursue a little calling myself. Is there a resource online with videos or soundbites to hear what different calls should sound like?

I'm not familiar with different types of calls available for ducks and geese, are there any specific aspects I should be looking for in buying a call?