Is there any category/page content preview widget Plugin?

Hello, am looking for a plugin that can enable users on my site view contents from selected categories/pages on the sidebar of the site. If a user/guest goes to a certain page or category, he/she would be able to view other contents from that category/page alone. The contents would be auto-updated. Does such kind of plugin exist in the wordpress plugin realm?

I would be very grateful if someone can point me to where I can get it. Thanks