This would automatically make images smaller with an option to click to make it bigger. People post/embed images that are so darn big it stretches my browser even though it's 1920x1200. I think you know the benefits. The forum is rocking 3.7 so this is listed that it'll work. I can't see the attachment because I'm not registered and I believe you need a serial number to register, but this should be the plugin I'm referring to.
http://www.vbulletin.org/forum/showthread.php?t=184571
Cheers