I have seen photos of a hang glider that was modified to have spoilers (or "spoilerons")1 on the top surface of the wing for better roll response. The spoilers were controlled by sliders on the control bar, and both could be opened at once for extra drag to increase the descent rate. The spoilers were hinged at their leading edges, like typical spoilers on airliners, not rising upward out of the wing like "blades" like the dive brakes of some sailplanes or like the spoilerons used on the P-61 Black Widow.2
They were fairly narrow in chord, and I believe they deflected up to well over a 45-degree angle.
This hang glider was a traditional "flex wing" design, where the non-fabric parts of the airframe are comprised only of an aluminum leading-edge tube defining the swept leading-edge of each wing, and a spanwise "crossbar" connecting the leading-edge tubes at about mid-span (and forming a strong triangular structure with corners at the apex of the wing and at each of the two junctions between the leading-edge tubes and the "crossbar"), and a fore-and-aft "keel" tube, plus the triangular "control" frame and the kingpost, and steel wires running from the top of the kingpost and the corners of the control frame about to the midspan area of the leading-edge tube. Also there were shaped aluminum "battens" (like the top edge of a traditional wing rib) inserted in pockets on the top surface of the wing. The fabric of the wing was also stiffened by mylar inserts curving around the leading edge and running aft about 12" max on top and less on the bottom.
Anyway, you can see how the fabric trailing edge would be very flexible, and a traditional aileron would only make a servo tab effect that would bend the wing in the opposite direction, negating most of the effect and making some amount of wrong-way effect. So the spoilerons were mounted about midspan, and quite far forward, just about 8-12" (as I recall) aft of the leading edge, where the fabric was not free to flex due to the close proximity to the stiff mylar insert that curved around the leading-edge tube. The spoilers were on the top surface of the wing only.
The pilot reported an effective boost in roll response above that available from pure weight-shift alone.
Obviously in this case the (lack of) stiffness of most of the wing surface played a key role in determining where along the wing chord the spoilers would best be located. Their spanwise location was further inboard than would be optimum in terms of maximizing roll control, but was selected to avoid pitching up the glider when deployed. (The outboard portions of the swept wing of a hang glider are well aft of the C.G., even near the leading edge.)
"Rigid wing" hang gliders constructed with a strong carbon-fiber "D-tube" and fully defined traditional wing ribs have minimal flexibility to the portions of the wing aft of the leading edges, so their spoilerons are located further outboard for better roll control power. They are also located further aft along the wing chord, and deflect upwards only a modest amount, acting somewhat like a cross between an aileron (but moving upwards only) and a spoileron-- presumably this has been found to produce less drag than a pure spoileron design that rises up to a position closer to vertical. The spoilerons do produce some amount of pitch-up tendency due their outboard location behind the CG, but this is minimized by the modest sweep used in these designs. Alternatively, some rigid-wing hang glider designs use actual ailerons attached at the trailing edge itself, while still relying on weight-shift for pitch control. However, a disadvantage of ailerons over spoilerons on a long-spanned, slow-flying, tailless, rudderless "flying wing" design is that ailerons tend to produce "adverse yaw", while spoilerons generate a helpful "proverse" yaw torque.3
Generally any spoiler that can be used for roll control (by deploying it but not its twin on the other wing) is called a "spoileron". Devices attached to the trailing edge of the wing are usually not called "spoilers". However, in the radio-control modeling community you'll find the word "spoileron" to mean an aileron, mounted at the trailing edge of the wing, that is also used to increase drag by raising it and its twin on the other side of the wing at the same time, in contrast to a "flaperon" which is an aileron, often full-span, that is also used as flap to increase drag as well as lift, by lowering it and its twin on the other side of the wing at the same time. Model airplanes (typically gliders) with surfaces deployed in "crow" mode feature flaps or flaperons inboard, and spoilerons (in the latter sense described above) outboard. So, the word "spoileron" has acquired two rather different usages. The first usage noted above, denoting a spoiler mounted forward of the trailing edge of the wing but used at least in part for roll control, is arguably more correct and more broadly accepted in the aviation world, and it's the one that is used in this answer.
Photo of "circular arc" spoilerons used as the primary roll control surfaces on the P-61 Black Widow-- they were located aft of the wing spar, and basically rose out of the wing like vertical blades, but also curving forward slightly-- http://www.maam.org/p61/images/ntwo%20new%20spoiler%20panels.jpg , from http://www.maam.org/p61/p61_rest.htm . "Circular arc" is mentioned here-- https://en.wikipedia.org/wiki/Northrop_P-61_Black_Widow#Design .
Rigid-wing hang gliders controlled by spoilerons are designed with dihedral as well as sweep, to help harness "proverse yaw" to create a helpful roll torque. Those controlled by ailerons never have dihedral and often have some anhedral to minimize the unhelpful roll torque generated by "adverse yaw"-- as do modern "flex wing" hang gliders controlled by weight shift, which also experience some degree of "adverse yaw".