Bob,
From your picture your between a rock and a hard spot, or its the old trying to put 10 pounds of stuff in a 5 pound bag....
If you can not find another place in your domicile for this 'nice stuff' then its a compromise most of us just could not live withe and
we would most likely take up fishing

IF this is the ONLY place for this stuff, then your stuck with the suggestions of the posts so far, mucking with the treble etc...wall treatments, I am sure
that would go over well especially if your stuck in this corner!!!
There must have been a reason for you buying these 'large' speakers in the first place, and I assume you want to listen to good or great sound etc....
There are some soluitions that would be better in this very small area:
One of them I know of first hand and have helped install 4 of them in 4 different locations all sensitive to big 'ugly' speakers (YES there are those that hate the boxes no matter what veneer is on them}

....
It would involve gettng rid of the speakers you have and replacing them with a different solution.
Take a look at
www.orbaudio.com, in you case their mod1 offering would work well for you based on that photo.
http://www.orbaudio.com/index.asp?PageAction=VIEWPROD&ProdID=2I have a set of the SongTowers in a seperate room and can play to my hearts content...but downstairs in a large open airy 18 ft ceiling room I have a set of these exact same small speakers and sub that we use everyday for TV viewing, satellite and an occaisional DVD or cd with the grandkids.
They come in all colors and mounts for wall floor etc....you can out them on rather small, releatively 'skinny' tubular stands very cheap and move them apart if needed.
If your receiver has a auto calibration mode, you could try calibrating this way...
The end result here may be better than selling all your stuff and putting a BOSE Wave Music system where you center speker sits!!!

Any how, best of luck!!
Alex