There are so many types, here are some:

http://www.amazon.com/No-Mortise-Bed-Rail-Fittings-Set/dp/B003F0DZZ4/ref=pd_sim_hi_1?ie=UTF8&refRID=1S7FT7E3DJJ5132V1ZKZ

http://www.amazon.com/Surface-Mount-Rail-Brackets-Complete/dp/B001DT3SLU/ref=pd_sim_hi_4?ie=UTF8&refRID=1S7FT7E3DJJ5132V1ZKZ

http://www.amazon.com/Locking-Safety-Rail-Brackets-Full/dp/B001DSZWN8/ref=pd_sim_hi_8?ie=UTF8&refRID=1S7FT7E3DJJ5132V1ZKZ

http://www.amazon.com/Galvanized-Steel-Bed-Rail-Fasteners/dp/B001DSZGCU/ref=pd_sim_hi_9?ie=UTF8&refRID=1S7FT7E3DJJ5132V1ZKZ

http://www.rockler.com/heavy-duty-wrought-steel-bed-rail-fasteners-4-pack-select-size

http://www.rockler.com/locking-safety-bed-rail-brackets

http://www.rockler.com/surface-mounted-keyhole-bed-rail-brackets

http://www.rockler.com/5-surface-mounted-bed-rail-brackets

http://www.rockler.com/surface-mount-bed-rail-brackets

Just browse the related items or use those keywords to run a Google search.

Also, I'm plugging /r/woodworking