One of the best recent ones is for sure Eden Lake. I was shaken for weeks, and literally could not stop thinking about it for weeks after that. I would also recommend Switchblade Romance, and Frontier(s), both are French, both are fucking insane, and have nice subtexts. Switchblade has a killer twist as well. I would also recommend Them, which came out a couple of years back, which is a suspenseful but non-gory killer feature. I also love Wolf Creek, Ringu, Dark Water, A Tale of Two Sisters, Pulse, Ginger Snaps... Steer clear of "Mum and Dad" which came out recently. One of the most repulsive and conversely boring films I've ever seen.