Screen space reflections
A completely free and open source screen space reflections image effect created by Ben Hopkins.
Get the effect from Ben's github, here:
If you want to read about it's implementation you can do so on Ben's blog, here:
This effect by Charles Greivelding may be worth checking out as an alternative, but I haven't been able to get it to work:
Note: Unity 5.3 will supposedly also ship with an offical SSR image effect.