That's pretty minor, I'm a mechanic by trade and I remove a lot of broken bolts. With allen head bolts I usually drill them out, just like in the link above the head will snap off and unless the threads are rusted in it will turn out easily. If you have an electric drill and a bit set it's very simple just hold it straight and take it easy I can assure you it's much easier than it seems.
If you can find them, I sometimes use left handed drill bits for smaller screws, The bits spin backwards to cut and usually the bit will catch in the screw and turn the bolt out so you don't have to drill all the way through. Sears might carry them, they usually come in smaller sets maybe 5 or 6 bits in a set.
Slotting the top of it with the Dremel tool works as well but watch out for those tiny cutting wheels, There is no guard on the dremel and they break easily and go flying, I almost caught one in the side of the face one time and I won't use them anymore.