i have see some of my domain expire if i not renew then i see it will see some advertise page.. i have see lots of site this type of advertise like this http://www.kites.com/ who purchase this type of expires domain?
expired domains normally set to parked pages of registrar. so u can see ads. 30-35 days owner can renew after that it even can be sold in market by registrars any one who have interest with that name will buy