LoopNet actually has the ability to include your properties via iFrame. I know its not the best and you don't get SEO benefits but it gets the job done. I currently use it for a client on one of my older sites.

check it out.
http://teamjuanuribe.com/commercial_forsale.php


You can check out the product called Looplink http://www.loopnet.com/xNet/MainSite...nk/?Feature=b2

You can also have LoopLink create a page for you on their servers that looks like your website for a one time fee.

Glad to help :-)