I'm always surprised that urinals (especially so-called 'waterless' urinals) haven't taken off more in residential settings - they don't take a huge amount of space, can pay for themselves in terms of water costs relatively quickly if you have metered water and enough men/boys in the house and don't present any particular new issues in terms of dealing with waste.

For toilets, gray water systems (using waste bath/shower water to fill the toilet) equally achieves savings (at a cost of space) without people needing to do anything different.