We saw a bubble fountain on a tour of a local elementary school several years ago. It was installed at ground level and almost appeared as a natural spring. We've been smitten with it ever since, but didn't know what to call it until we stumbled on this DIY from FreshHome Ideas.
It requires only a fountain kit, a water well set into the ground, and rocks to cover it and act as a place for water to trickle down and make its magical, relaxing sound. Now, there's nothing stopping us from having a baby like this up and running for next spring!