My present to my wife this year for her birthday was to build her an outdoor sink - a place where she can clean off her garden tools and wash vegetables before bringing them into the house. We had an old washtub that we weren't using and a bunch of cedar left over from our new deck so I took inspiration from this blog post over at Bonnie Plants. Mine doesn't look much like theirs, but I really liked the rustic appearance. Because mine is tucked under an existing deck, I wanted to use the back side for storage. That, coupled with the fact that the ground underneath is not level, added some engineering challenges to the build, but I'm happy with the results. More importantly, my wife likes it too. I'll add some more photos when the plumbing is complete.
[Update: 7/6/19] So the plumbing got complicated and the weather got cold, and I had to wait until now to have a free weekend to finish it up, but I'm really happy with the results. And, more importantly, so is my wife. Because the backyard faucet comes out of the foundation of the house, and my sink is a good 10-12 feet away from it, I am using an Armadillo hose and some quick-connect couplers from Lowes to get water to the sink. This allows me to leave the water on all the time and not worry about the hose bursting, and to easily disconnect the water in the winter.
Then I ran some galvanized pipe on the back side to split the incoming water for the faucet on top for the sink and a another faucet at the bottom left for a standard garden hose.