Heh... I was shopping for sprinkler stuff this weekend and came across these. I had never heard of them, wasn't looking for them, and wondered why anyone would need them, but I guess now I know.
I can't seem to find the original site I was on at the time and I'm not even sure if this was the same part, but it's the same principle....
http://www.amazon.com/Orbit-Sprinkler-System-Impact-53161/dp/B000VJDXHC
<edit>
Sorry, just realized this was a pretty old post.