It's not completely free, and not completely open source, but we've been very happy with Octopus Deploy https://octopus.com/
That and Topshelf https://github.com/Topshelf/Topshelf have made deploying Windows services very easy. Topshelf is slowly adding some Linux/mono support, and OctopusDeploy supports SSH as a deployment option, but unsurprisingly things aren't as nice if Windows isn't your target.
