We only have a small, dead thread for light novels so I thought I'd drop this here instead:
Otherside Picnic is extremely good and I highly recommend it. Three volumes are available on BookWalker and Kindle, but if you absolutely don't want to spend money the first two volumes are on Nyaa. It's well worth the money, though.
It's a horror yuri series where the horror is well-written and the yuri appears to be going somewhere. I'm having trouble explaining how good it is without spoiling... The creepiest chapter for me was the third one of the first volume, but individual opinions will depend on your phobias and personal experiences.
An anime was announced by the director of the Kase-san OVA and the studio that animated Hanebado, so it has chances of being good, if you don't feel like reading novels (but you really should read them).