Not a shower, but just a foot wash. Turn a switch on and water sprays out to clean your feet before you get in the boat. My dads 26' Ultra Shadow Deck has it & I would like to see about doing it on my Mondo.
Looks like this (I took it off Ultras website so it's grainy and zoomed in)
http://i3.photobucket.com/albums/y81...A6236BD7AE.png
You can see the rocker switch and a nipple on the sponson that shoots out water. It's awesome!
I can't find anything about this though. Google didn't help...