Hellobee Boards

i don't, but these ones are pretty neat, though a little spendy except for the wall shelves

http://www.amazon.com/Bowser-Cat-Tower/dp/B00470VM06/ref=pd_sbs_petsupplies_50?ie=UTF8&refRID=0SWRJ1ECBH6W7YXMBVY1

http://www.amazon.com/The-Refined-Feline-Lotus-Espresso/dp/B004BA6LSK/ref=pd_sbs_petsupplies_1?ie=UTF8&refRID=10TKHB19VR38G883ST2Z

http://www.amazon.com/The-Sebastian-Modern-Tree-Black/dp/B008GWSJGG/ref=pd_sim_petsupplies_1?ie=UTF8&refRID=0GMHQ7JZ006944YBVWQS

http://www.amazon.com/The-Refined-Feline-Shelves-Off-White/dp/B003VH7SVS/ref=pd_sbs_petsupplies_46?ie=UTF8&refRID=0GNRV1CJ6CZ50XZGE0FZ

There are a bunch of Ikea hacks online for cat shelves using Lack shelves http://www.hauspanther.com/2012/12/31/simple-and-elegant-diy-cat-climbing-shelves/

If your cats would use them, they seem to be a nice idea especially as they don't take up any floor real estate!