Dog Park fundraisers:
Dog swim: at the end of the summer season just before the pools are drained for winter is a great time for a doggy swim. Many dog parks use this opportunity to host a dog swim event to raise money for the dog park or local animal shelter. Some of the doggy swim events set aside a separate time for small dogs. Admission is usually about $10 from what we hear. We hear that this is one of the best fundraisers.
Pub crawl: we have only heard of a few of these events but they seem to get a lot of people interested in the dog park. Here is an article about one very successful pub crawl with 285 people in attendance that raised $6,425 at $30 per person to attend 10 local bars and restaurants.
Dog walk-a-thon: these are done like any other walk-a-thon but the dogs get to participate.
Dog photo days: we have heard of photo opportunities for dogs with Santa Claus, the Easter bunny, football mascots or jerseys as superbowl time... These usually cost about $10 for a photo.
Just some ideas to get you started. Please list any other events you have been to in the comment section.