I like Jay and Zachs suggestion of some kind of photo tour /workshop.
The problem with recommending gear, is while we can list quite alot of nice stuff within your budget, we dont know a) what he has other than Canon and b) what types of photography he enjoys.
So it spossible we could recomend something really nice he may not be able to use or already has something similiar, and or not in line with the style/type of photography he enjoys.