I do find myself wishing so very often for a time machine to go back and take GFDL'able photographs of historical events, scenes, stuff ...
I've uploaded a fair number of fair use, or permission-and-fair-use, images of historical things to Wikipedia where I've had no luck finding an image available under a free license and it's impossible to photograph it now, but I hope for a day where this is no longer necessary, and I am forever on the lookout for images and the opportunity to persuade photograph owners to help Wikipedia.