I need to get a 2nd flash for doing product shots.

I have a Canon 60D and a 580EXII unit, but need another unit to do some fill on the side.

While I love my 580, I don't need such a strong and sophisticated unit just for some extra fill light as the 580 is used for the main lighting, and was thinking of saving money and getting a Metz or Nissin or similar.
As it will be left at work, most of the time, I don't want to pull what remaining hair I have out, if it gets dropped or damaged either.
However, I do want the new flash to work wirelessly with the Canon built-in wireless. This is a MUST.

Do any of you learned people know which flash, apart from the Canon range, will work wirelessly with my camera?
It doesn't need to be very powerful, and I'm trying to save pennies right now, hence wanting to go to an aftermarket brand.