Hammock
The first thing my husband built for me when we moved here from the city was a sturdy, pressure-treated, last-a-lifetime clothesline that was just outside the cellar door, handy to my new washer.
It was never the plan, but one day when he had nothing better to do (and having noticed that I used the dryer more often than I used the clothesline), Tom bought some ready-made trellis from Home Depot and framed it on top of the two sturdy posts that had been my clothesline. Voila! A pergola under which I could hang a hammock--and I promptly did!
He'd made me a bench years before so that I could sit and enjoy the result of my labors. This is ever so much better on a warm day, to lie in the shade and see this view as it changes with the seasons.
Update: Record-breaking snowfall in February of 2015 piled high on top of my pergola. Strong winds from the northeast toppled the structure, snapping the legs in two. Bye bye hammock.