This would be of no use to you cityfolk, but well useful out here in the country. Dutch designer Floris Schoonderbeek's Raintap is a rain barrel that attaches to a drainpipe to collect roof runoff, as most rain barrels do. But it has the additional features of a sink in the top, powered manually by a foot pump down below. This provides a handy washing station that allows you to rinse off your hands, tools, food from the garden, etc. without having to take off your muddy boots to go inside.
Water draining from the sink can be diverted back to your sewage system…
…or outside through a pipe and back into the earth.
Alternatively, you can hook it up to a spigot, as a backup source.
Water that doesn't get used by the sink can be accessed from a tap on the side, allowing you to fill watering cans, buckets and such.
Made from recycled plastic, the Raintap runs €379 (USD $429).