I must admit I quite like the beer tab idea.
While I realize that a lot of people just like to be helpful and don't want any reward for it, there is another way of looking at things.
If you help someone, or add something useful to the site or an image and the people you have helped say thanks, then that is your reward.
However if they also volunteer to buy you a beer and that goes into the sites coffers for offsetting its running costs, I think you would feel extra proud to have worked towards the upkeep of the site and the benefit of all its members?
The more helpful you are, the more you could potentially help the site?
Perhaps a small league table could be made of the sites most helpful people?
At the end of next year a small portion of the funds could even be put aside for a prize for the most helpful member?
This is a very young site and I see no harm in encouraging people to help and participate in it?
You will always get members who join up, get what they need and then disappear again, if not at the moment then later as the site steadily grows?
Encouraging people to stay, beyond just getting the latest and best image, is something which all sites need to do?
As has already been said, in a way people can feel like they look a bit mean if they can only afford to make a donation of a quid or so, then they don't donate at all because as much as they would like to, times are hard for many people these days!
I am sure all donations are appreciated by the site.
However a universal way of showing your appreciation is by "tipping" people for their good service.
It may be that the site is well enough supported with the current donation system, so this is not needed?
In the words of the Tesco ad though "every little helps"!
Now I am sure both Sic and nao and anyone else that knows me will be thinking;
"here he goes again with the long posts"!