MiniStumble is a StumbleUpon Safari extension. It gives you a new extension bar with login options to log into your SU account, buttons to Stumble, Like/Dislike, Discover, Show Info and display Favorites. More features (like being able to select categories to stumble though, for example) are coming.
What's new in MiniStumble Safari Extension
I've altered the functionality dramatically. It no longer simply launches the StumbleUpon toolbar but instead actually pulls proper stumble results from the SU server based on your login. You can also Like/Dislike the current page, or Discover the current page. More features to follow.