Topic: Please allow overlay captions (like in PostcardViewer)
Even if flipside is the best invention in the history of the world, it has no value if - as many posters here stated - the average user isn't capable of realizing there's a flip button, let alone clicking it (even if they notice it, the "return" button suggests it's a "zoom out" button).
Besides, sites usually need users more than the users need the sites. So you shouldn't force users to double click everything. Most surfers have zero patience as there are endless other sites waiting for them.