The biggest reduction in our household water use was by changing to
Caroma "two-button" toilets (Caravelle 270), which use 0.8
gallons/flush on the "half-moon" button and 1.6 gallons on the
"full-moon" button. "half" often is enough even for "solid loads",
but we do find that we need to use a toilet brush more often to keep
the bowl clean. I'm also not wild about the style, but I've gotten
used to them. On the definite plus side, Caroma North America immediately
sent out an entire replacement mechanism at no charge when I e-mailed
them that one of ours was sticking. I picked up a lot of 3 (we have 3
baths in our house) for $650 on e-bay from ewins.com in Omaha, NE
about 3 years ago, but they are still available for about $285 apiece
elsewhere.
Finally, we are remodeling our (3!) bathrooms and in the process have installed thermostatic bath/shower faucets. We used a Grohtherm EuroplusII external faucet (with a shower attachment) which has a right-hand knob for temperature (that we adjusted once) and a left-hand knob to direct the flow either through the tub spout or the hand shower. This saves water, since it comes to the desired temperature as quickly as possible and it qualifies as an "anti-scald" protection device. I also think it looks really cool. I would purchase more (even though it was $450!), but Grohtherm has discontinued them (though they make similar products in other styles). I also have to admit that it was a pain to install. It had to be installed at exactly the right depth from the wall finished surface, with an offset fitting that could only point at one angle. Even so, it required a special wrench (unavailable in a city of 100,000, so I had to grind my own) to tighten the supply lines.
Our monthly water usage is typically 1,000 gal. in winter and 2,000 gal. in summer (when we have to water our lawn a bit).