SharePoint Classifieds Web Part

From Vinewave:

SharePoint Classifieds Web Part enables staff members to easily advertise items for sale on your intranet with the Classifieds Web Part, our complete classifieds solution for SharePoint 2010. People can view the latest items for sale, or browse classifieds by category. As a web part administrator you can set classifieds to expire after a certain number of days. You could create alerts to notify people when a new item is being sold. Or upload attachments such as user manuals or warranty slips to the items you're selling to give potential buyers a bit of extra info. You could even set up an approval process for new classifieds to ensure they're double-checked before going live on your site.