http://mockdraft.phillyarena.netWe did this last year, same deal. Click on the link for a description of the scoring.
I was going to re-do the backend on the site, but forgot. So the interface is still a little clunky, but it is fully functional.
You can edit your picks right up until the day of the draft (at which point I will close it and you can only view results).
If you registered last year, you don't have to re-register. Simply click the forgot password link to have a temp pass e-mailed to you.