If you're jammed for space, AquaC makes a hang-on that gets good reviews:
http://www.jlaquatics.com/cgi-bin/sh...ogno=ps-acremp
I used an Aqua-Medic Turboflotor 1000 multi on my 90, and had really good results with it. It can be used as a hang-on as well but needs a lot more space than the Remora Pro.
There are some very handy guys around who make some awesome skimmers, but typically larger beckett-style units. I think Canadian Man did sell an AquaC knock-off a while back...