We have been using dynamic types to create databases of various things that are ranked and commented on. Dave Bauer is on vacation this week and he is SG's expert on this.
Unfortunately none of the sites we have done this on are fully skinned and polished and ready to go.
It looks a lot like the LAMS community activity database:
We started with this code but moved it to dynamic types. I think the ratings and general comments pieces are still pretty similar.
We have also done ajax rating where you can drag the stars with your mouse, but I don't have that up on a site I can show publically. Hamilton can give you the code if you want it.