Nope, I've got all my 5.25" and 3.5" bays filled. Now I technically only have one internal HD bay since it would be dumb to put an HD directly above the small fan, especially with the screwheads for the fan just waiting to scratch and/or damage it. I also have all my card slots full, I'm maxed out :P
With this mod that I did though, HD temps are not a problem anymore (they weren't really before I guess, I'm just paranoid)

Just trying to show the cheapest fix... those rail extensions work great-- I've used 'em--if you have a 5.25 open.
it's good to know about anyway

I actually already have some, they came on an old PCMCIA drive, I'll probably use them elsewhere, on my planned server that I'm building (even though I don't really need one, I have the spare parts so why not...)