Mr Dude made this fun water toy with some PVC pipe and irrigation misters. I found the inspiration at PB&Joy. The entire project was less than $12 but the boys all love it like it's priceless. Of course, they don't know about the water bill, but it was so fun to walk through and get gently soaked. 
If you're interested in building your own walk-through sprinkler, you can visit this instructables site with all the instructions.
Have fun!
(the photos have my craft bog address on them...come visit me there if you're interested in crafty things!)
