Sony makes a 37" 720p lcd rear projection set and a 46" E3000 1080p lcd rptv, other than that the sub 50" size range has been taken over by plasma and lcd flat panels.
JVC won't even make one smaller than 55". - Which sucks. I didn't buy their last 50" one because it didn't have an adjustable iris. And now that all the JVC LCOS do have this feature they don't make one in 50".
(Sony does make a 50" one but that's as small as they go)