The latest toy from WordPress serves up a random post from your blog. Just add “?random” to the end of your blog URL. I should add that as a sidebar link. Try it out here.
Other new options are a tag cloud widget and drop-down boxes for other widgets. Nice ideas but perhaps rushed to release too early. I found the tag cloud to be big and ugly (with this theme at least) and the category widget drop-down is completely broken. Still, 9/10 for effort.
Update: the drop-down issue seems to be fixed now