Allen keys, Allen wrenches, hexagon keys, hexagon wrenches...and a few others I think...they go by many names.
Looks like it's going to be Eklind for me. I have a number of big Allen brand keys, things like 16 mm and 22 mm. 22 mm is the size for opening mercury flasks :-). I like the Allen brand keys, but their sets only come in a crappy vinyl wallet. I need better storage than that.
Chris