Aren't you talking about two separate things? User ratings and topic ratings are not one and the same, no?
We can go with the simple "thanks" and then give a cumulative "thanks" count in their profile.
I like this better than the star average method.
Or we could go with something like "Was this post useful? Yes / No".
Though basically similar to the star rating we have now, the verbiage "Was this post useful?" has more meaning AND it might encourage more topic rating participation... especially if you put the question and yes/no boxes in the topic display instead of burying it in a drop down menu. Perhaps at the bottom of the replies along with the topic menu? The only problem here is how would you disply the statisic with the topic listings - now you see the number of stars with the present topic rating method. Maybe a percentage?
And then the profile could give a total of useful / not-useful posts.
This is the part that would tie the two (user and topic) ratings together which I prefer being separate entities.
