I hated not being able to tell who actors were from the tiny images on IMDb's movie reference pages. This script shows an enlarged version of the image when you mouse over the actor's row in the cast listing. It also shows enlarged versions of the poster, photo, and video thumbnails along the top of the page when moused over.

I use the "classic" IMDb layout, but designed this script to work with the newer layout as well. (imdb.com/title/tt0056172/reference as opposed to imdb.com/title/tt0056172/.) Please let me know if you have any issues with either layout.

(Tested in Firefox with Greasemonkey and Chrome with Tampermonkey. Please give me feedback if you have any issues!)

Changelog:
0.4.2
Fixed issue with pop-up hiding

0.4.1
Set pop-up images to display no larger than the window

0.4.0
Several improvements to image positioning
Now attempts to keep pop-up images from displaying off-screen
Added support for "/combined" URLs

0.3.2
Fix to work with imdb's new ssl image server

0.3.1:
Works with imdb's deferred loading of images on full credits pages.

0.3:
Now also shows larger images when you mouse over the thumbnails at the top of movie and actor pages.

0.2.1:
Minor changes to work with newer imdb layout.

0.2:
Initial release.