I've done blackberry jam several times in the past, and might do another batch this summer, but I saw this recipe for blackberry syrup and thought I'd give that a try.
It was about as easy as can be, to be honest. I was psyched to try it in a drink a couple days later, and it was very fresh and tasty. This had gin, club soda, and syrup with some ice. Can't get much simpler than that. I might try it with tonic sometime soon though, add a bit of complexity.