Canon Speedlite 220EX, 430EX II or 580EX II external flashes will work with the SX10IS that you have. There are also other manufacturers that make flash units but you will need to make sure they are compatible with Canon cameras. One such unit is the ProMaster 2500EDF Digital which offers a tiltable flash, but it doesn't swivel to the side like the more pricey units.
Steve M.
