Any actual implementations of this (or other superresolution algorithms) to play with?

There's the waifu2x project [1] which also uses neural networks for super resolution. There's also the MPDN extensions project [2] which has various kinds of image scaling methods. It depends what kind of algorithms you want to play with really.

[1]: https://github.com/nagadomi/waifu2x

[2]: https://github.com/zachsaw/MPDN_Extensions