If you live near the Aquarium of the Pacific in Long Beach, you may want to consider getting an annual pass. For only $110 a year, an entire family can get unlimited admission. This includes 2 adults and any dependent children in the same household. You can also get 5 parking passes for only $15 (parking is normally $7 each trip). In addition, they often have a promotion which includes 1-2 free guest passes when you purchase an annual membership.
However, you can also get FREE admission once a year if you work for a non-profit organization. The only catch? Your HR office has to fill out the form and send it in, and then the admission is good during the month of September. In order to qualify, your application has to be received by August 8, 2008. For more information, visit this site.
We have passes to the Aquarium and can tell you from first-hand experience that our kids love it, and it is great to be able to go for 2-3 hours at a time. It's not Sea World, but it's sure a lot closer to us! :)