Nestled in a residential neighborhood in the Hayward hills, this nature center has an animal lending library on the weekends. On a first-come, first serve basis, you can borrow mice, hamsters, guinea pigs, and rats as pets. For $20, you get to take a cute rodent or two home, along with their cage and food for a one-week rental. The fees go to support the center, which serves as a shelter for wild animals. Even if you don't feel like having an erstwhile pet, Sulphur Creek is a fun place to see an impressive array of native rehabilitated wild animals including coyotes, a golden eagle, falcons, owls, a turkey, chickens, rabbits, snakes, and amphibians. Entrance to the park is free (where you can view the animals) and it's a popular spot for kids' birthday parties. Whether you are non-committal about pets, or want your kids to learn how to take care of some, this is a great place to test out the waters.