I've seen it used by Elite Aquatics as well. In fact if you drop into the shop they have a few on display with that glass on the overflow box. I think they do it for effect. I don't mind it, looks kinda neat :-)

tank
 

another option you could do is get some solid hemlock crown molding and attach it around the sides and front-it would give you 2 1/4 " all around and you could stain it to match it to your cabnet-cost about $3-$4 a foot

That tank was NOT build by Bow Valley Services.

Very good idea, be sure to attach with glue and screws.