Here's a link to a thread pertaining to a cabinet I built, which is really quite nice and overall fairly stealthy. You could probably flower in it (although I built it for vegging), just by swapping cool tubes for warm ones. Or by putting two 400 watt lights in there in cooltubes. Might need a tad bit more height for flowering, even with ScroG, although I've seen it done with less height than this box. Not enough room for any 4'x4' systems, but I know for sure I could fit 18 3-gallon square pots in there, if I needed to.

http://boards.cannabis.com/closet-ca...g-cabinet.html