Wifey wanted sparkling water on one of my 6 taps. I was skeptical, as that means less beer, but I obliged earlier this week. Filled a keg with filtered water, hit it with 45psi and shook the hell out of it, then backed down to 35psi for serving. It took a couple days to get to truly "sparkling water" carbo level, but I gotta say: having that around it so badass! We finished the keg in like 3 days. I think I also drink less beer because of it too, for some reason...there's something about the carbonation that just makes it much different than still water for me, much more satisfying.
Anyway, if you can spare the tap space, I highly recommend it!!!