Attention: this block is deprecated and will not work for concrete5.6.0 and later sites. For alternatives, check out:
A powerful version of the randomizer block that lets you automatically cycle one peice of content however often you want to. Joke of the hour, quote of the day, anything like that is easily possible with this add-on.
This also comes with two large scrapbooks of content, a huge pile of Mark Twain quotes and a huge pile of Christian Scripture.
Be sure to check out the Randomizer, the guts of which are included in this add-on.
If you would like to make some changes to the add-on, the code is up on github.