Honestly anything is better than what we have now - which is NOTHING. Nobody is going to take BTC seriously if the currency is seen as being super risky - in the sense that there is no recourse against theft.
What you described can be useful as long as the reputation and rating system is robust and secure.
To be honest I'm surprised nobody has created any such service. It would be fine for me if it was for profit. I for one would gladly pay a percentage of the funds recovered if I can have them back. There could be a LOT of money in it for any company/organization who sets this up.
Another thing that could be useful would be a website that does in a more professional, detailed and graphical manner the same thing my C program does - track bitcoins. Once again I and no doubt many people would pay for this service. So my point is that there is a lot of opportunity for bitcoin security entrepreneurs. But sadly I get the impression that those who are intimately familiar with computer security and far more busy figuring out ways to STEAL bitcoins instead of how to legitimately EARN them. I could be over-reacting here and may be wrong on this wide generalization, but anyways, thanks for sharing your ideas mrb!
I don't see much profit in it. There's no way that such a company could recover the funds, even if they were labeled as stolen. And all someone would have to do is some quick laundering if they noticed some of the coins they had were on the list. Sending them to a couple of exchanges, then back to themselves would suffice.
That said, I would like to build a tracker program with some reasonable statistical analysis. People would be able to outsmart it, but for the most part, you would be able to see what addresses/coins are associated with a particular address. It would be a fascinating analysis for sure.