We wrote up the Playground Founder site way back in 2008. The basic mission -- a user-generated list of playgrounds throughout Australia -- hasn't changed, but there's a couple of enhancements that make it worth another visit.
In our original writeup, we noted that the site didn't have Google Maps integration. That's now a standard feature, making it much easier to locate any given park. There are also handy lists showing playgrounds in a given category (such as around a given area or on a route between two cities).
For finding rest stops on the go, there's also a free iPhone app, which locates the nearest listed playground. You can automatically upload additional playground pics to the site through the app. An Android app would be nice, but for parents seeking a break from "are we there yet" commentary, the site and/or iPhone app seem pretty essential.
Playground Founder iPhone app [iTunes Store]