[meatgel]

You can set different ringers for each person in your contacts by editing the contact and scrolling down to *I think* right below "mobile number" ... next is "ring tone" ... if you click on that you get a drop-down list of your ringers.

To have separate ones for blocked and unknown you'd have to have a separate program I believe. There are quite a few programs, but the first that comes to mind is Photo Contacts Pro.