Set it and forget it! Rated 5 out of 5 stars
Great concept it would be my #2 add-on if it wasn't for the fact that, when set to random select from favorites it resets the setting after every restart. Need's to auto sync with favorites or sync from a locally stored list of favorites.
Just a suggestion for Mozilla those who have installed personas under their themes list using Firefox 3.6 and are using this extension you could add an option button near "use theme" button , saying "add to favorites" which would then add it to the locally stored list, so online auto sync or login wouldn't be needed.