Hi bruce,
there are a few options - Lexicon used to make (and probably still do, though I've not seen one around for a while) a half rack box called the LXP-1, which has brilliant reverbs, as well as a few other sounds, but not the bells and whistles of the MPX-1 or MPX-G2. The new Lexicon MPX-100 and MPX-500 are also well worth investigating, though as 1U rack units, they do take up rather more space...
WRT the stomp boxes, I think there's a rather good DOD one, which (like all the BOSS pedals as well) will run off a mains adaptor instead of the batteries. I tend to avoid battery effects if at all possible (the line 6 DL4 has the option to power with Batteries, but I only used that while at NAMM to avoid the power supply problems. the rest of the time, I use the power supply.)
i don't know if Carl Martin or EBS do a reverb, but my experiences of all the other pedals by both companies has been fabulous.
If you're looking on the second-hand market, the ART Midiverb, Alesis Quadraverb and the Yamaha SPX-90 (or 900 or 990) are all good quality 1U rack boxes...
I hope that lot helps! :o)
cheers
Steve
www.steve-lawson.co.uk