We are exploring non-ad based revenue models primarily, but, are open to tastefully done ads like you have described. We have plans on greatly enhancing our gear section (can you tell it hasn't been touched in two years?) to encourage more detailed inputs. This will let us do more relevant targeting. If we do ads, I want to attempt to only show ads that are beneficial to a user. Since we are location based, that means maybe only allowing local ads for users, or maybe any ad as long as it is a sweet deal. Users might not be turned off on ads if they are for 25% off stuff the want anyway.
As far as donating, I am working out how I want to handle early donors considering we are nearing the launch of paid accounts. We will be treating our early donors well, they will receive much more than they might otherwise for a normal paid account, but we haven't put any actual "policies" in place. I am constantly surprised by the levels of donations. We received a $200 donation at the end of last week from a single user! The average has been around $22.50 - I have intended on writing a blog piece on it, but haven't managed yet :)