Don't forget about carnivorous plants, alot them them love the moist conditions a paludarium has.
Do you happen to know what your humidity range is? My paludarium has constant 99% humidity and the glass is almost always covered with water droplets. If you have high humidity you need to be more picky about what orchids you put in there and where they go. Water will collect in the wrong place and will cause rot.
Probably one of the easier ones would be Epidendrum porpax.
I have killifish in mine and they seem to love it.
Check out the Terrarium Gardening forums here also, there is alot of good info in there.
And for further information over load, check out
http://www.orchidboard.com/community...errariums.html