I'm curious if anyone knows where I could find
a SMALL steamer (to fit on a 6" ledge)

Your Pyrex dish sounds perfect--easy to clean, easy to see water
level, fairly easy to clean, no rust, inexpensive. If glass is hot
and dry never get it wet until it completely cools to room
temperature.

I'm using a 5x9 pyrex baking dish, which works well for adding moisture to
the air, but it's when I need to add water that I get nervous. I make sure
to add water before it gets empty, and try to get the water as hot as
possible from the tap before adding it, but I still worry about it
cracking.

I'd also like to find something that "looks" a little nicer.

Anthony