Somewhat bothered by the amount of Radium, in my community's water supply, and generally digging the whole “clean” water thang — buying the cheapie bottled water cases whenever they're on sale — I started looking around at under-the-sink units. After much reading I found a reverse osmosis unit (RO2000 Series B), made by Omnifilter (http://www.omnifilter.com/). On sale for $157.98 locally at Menard's (home supply store), it looks relatively easy to install, per the manual (http://www.omnifilter.com/Owners%20Manuals/ROSystemManual2006.pdf) I downloaded from the site. It has a separate faucet that I'll need to install, next to our standard faucet. I'm actually looking forward to doing it.
I'll let you know how it turns out.