Software Hut's been gone for the better part of a decade, or close to it. Their website stayed up a lot longer than their actual operation did, but occasionally you could email them and still find parts. AFAIR someone bought up the remainder of their inventory, I recall seeing photos of a van full of stuff, but can't recall who or where.
It's interesting to pick up a copy of Amiga Future every now and then. There's ads in there for companies I'd never heard of before! Sadly all of them are in Europe, as far as I know.
Just flipping through a copy next to my desk, here's a few to get you started:
Alinea Computer
www.amiga-shop.netAmigastore.euAmedia France
amiga.amedia-computer.comAmigaKit
www.amigakit.comVesalia
www.vesalia.deSearch the forums or google, as Dan said, for a more complete list. Of course there's also ebay, Amibay, etc.
I've ordered from three of the five companies I listed above and never had issues with any of them. Sometimes you have to shop around depending on what you're looking for, for example AmigaKit was out of stock when I wanted to buy an X-Surf 100, but Amigastore.eu had one. Either way, it's nice that we have options, even if they are all in Europe!