As promised, I'm getting ready to launch a new version of Yahtzee with personalized statistics and a new design. I'm still working on some new features and I haven't tested it well in anything other than Google Chrome (my preferred browser and by far the most popular in this case), so I'm sure there are still issues, so I'm calling it a public beta right now.
You can check it out at yahtzee.silentmatt.com/yahtzee. Let me know if you run into any problems (be sure to let me know what browser version you're using) or have any ideas for improvements. You can play "anonymously" but if you want to keep track of your own statistics, click the "sign in" link to create an account. You can sign in with a Google account or OpenID.
Note that any games you play in the current version are automatically imported into the new version, but they won't be counted toward your personal statistics. Also, games played in the new version don't get counted in the old one. The mobile version doesn't let you sign in or view your stats yet (or any stats for that matter), but if you are signed in from the "full version", the games will still be associated with your account.