I have most of Olson Quarter Horses' advertised horses for sale at Equinenow.com (the link brings you directly to our page). Of course you can also check the website.
I also use a bunch of other sites like dreamhorse, horsetopia, equine.com ect. But I really like equinenow because of their free picture adds and the huge amount of traffic they get. They also make it easy to post stuff to craigslist.org and share with twitter ect.
I will notify when I post a new horse for sale on here too, but there you can see all the recent horses we have advertised. Many of our broodmares are also for sale private treaty and they are just on the website, since we are planning on downsizing the herd over the next couple years.
Thanks for visiting!