That all depends on how you define content filtering. If you mean by an IP address, sure, a simple standard or extended IP access-list can do the job. If you mean by URL, no. You'd need a third-party application that can do the name-to-IP address resolution for you, and intervene once the IP address is known.
As for the chat using port 80, again, that one is probably not going to be possible. All the router can filter on is source/destination address/port. The router can't tell the difference between a port 80 packet that contains a web page or a port 80 packet that contains chat. Given that a particular chat host that uses port 80 probably has separate boxes for their web server and chat server, again, if you were able to resolve the name of the chat server, you could filter out the chat address but permit the web address, but the architecture of that site is completely out of your control.
