Specifically, what hot shoe accessories are available for the T3 / 1100D that use the hot shoe electronics to communicate with the camera (besides flashes)?
I'm not quite sure exactly what you are looking for. There are only a few main things that I commonly see hot shoes being used for these days:
In the past I have seen them used for a few other things, but this is much less common:
Since you don't specify any particular need, that is about all I can tell you:)