60D External Flash
What about a flash designed for an Olympus digital - the FL36R?
Is it worth a try?
If it has a non-TTL Auto mode, aka 'thyrister' type function, then it'll be usable with the EOS body in Av or M mode. Just coordinate the aperture and ISO settings between the speedlite and camera. Or set it for manual output mode and do flash exposure completely manually.
But more generally it isn't worth the bother. The hotshoe pin layout and electronic communcation are different on EOS and Olympus cameras. The AF Assist light of the FL36R will not work, the auto zooming won't work, it won't work in TTL mode, etc.
Unapologetic Canon Apologist