One of the more unusual Firefox extensions you're likely to see is Tumbarumba, a "frolic of intrusions" that hides 12 new short stories in web pages you're browsing and reveals them to you a little bit at a time.
The plugin is actually quite simple, although its description as "a conceptual artwork in the form of a Firefox extension" may suggest otherwise. Tumbarumba inserts story fragments into random web pages, creating sentences that flow grammatically but otherwise make no sense. Upon noticing the out-of-place sentences, users can click on them to reveal a small piece of one of the 12 short stories; further clicking unveils more and more of the story, until after several clicks the web page is completely replaced by the story, formatted in the style of the original page and including pictures from Flickr.
"Our intention is for the reader to not only have the pleasure of finding and reading the stories, but also the momentary disorientation of stumbling upon a nonsensical sentence as well as a heightened awareness of textual absurdities (of which only a fraction will be the result of Tumbarumba)," the plugin's website says. The stories in Tumbarumba are written by authors including Greg Van Eekhout, Tim Pratt, Jeff Spock and and Mary Anne Mohanraj.
For those who value their productivity, the extension's effects can be turned off for individual websites or completely. A video tutorial is available for people who want to see it in action, but the best way to learn about Tumbarumba is to simply install it. Aside from the addition of a Tumbarumba menu, the effects won't be immediate or obvious. "The idea is for it to occasionally mutate a webpage's sentence and cause you, the reader, to a moment of confusion & delight," the site says. "You can actively hunt for Tumbarumbas, but we think it more fun to stumble upon them unexpectedly."