I'm just wondering if there is anyone out there that has found a Wireless router (something similar to like a linksys/d-link wireless router) that is able to be mounted in a rack?

d-link and linksys make routers for the consumer market and most likely do not make routers what would be able to be mounted in a rack.  i've googled for it and have't come across anything from them.
 
if you wanted a rackmountable device, you would probably have to look at the small business routers, like the lower end cisco wireless routers, and sonicwall routers, etc.....

Im far from an expert, but from what Ive seen as you move into the type of scenario where most users would have a rack, you wouldnt use a 'wireless' router, you would have wireless APs feeding into a traditional router.

B-Unit would most likely be correct on this...most wireless AP/routers are of the home sort...any time you start talking 'rack mountable' you begin moving into the business segment (most people, sans uber network enthusiasts don't have network racks in theirs houses).  You would then be talking business class routers with network AP in your LAN.  Now...that's not to say you can't 'make something work' with a little ingenuity.