I might be dumb but...

[NightSpirit]

http://cgi.ebay.com/ws/eBayISAPI.dll...category=26261

250 MH for ~ $100. So thats 500 watts for $200.
It says "listed for wet locations".

Am I going to catch on fire if I put 2 of these over a glass
top on a tank? Will this even work?

No, I'm not running corals yet, but $200 sounds a lot better then $500...

[loganj]

I don't see why it wouldn't work OK. I probably wouldn't use the glass tops due to the heat buildup though. Maybe suspend the fixtures over the tank as pendants? As long as the fixture will accomodate aquarium bulbs and I don't know why it wouldn't, it should work...you'll have to buy bulbs as I'm sure you already knew. The ones that come with this fixture won't be suitable for aquarium use due to their color temp. I'd get more opinions before I bought one though. There are folks on here who have forgotten more about MH than I know at this point 8O . Keep us posted...sounds like a GREAT deal to me.