Quote Originally Posted by knutb
Egg-turners - cool idea..!.. Didn't think of that one - maybe because i didn't know that such animals actually exist
Chickens? Yeah, they're something I've been working on for a while now...

But seriously, here's a link to one. It's the first link returned by the search, I know nothing of the manufacturers product specifically:

Automtic Egg Turner

For what it's worth, do NOT use these for your incubating eggs, the mortality rate will be astronomical. Can't say if the same would be true for your negatives.