Kind of annoying, isn't it?
Thankfully, there is such a browser extension that automatically enlarges, zooms in the photo currently being hovered, making Facebook less of a hassle!
FB Photo Zoom: Lets You Zoom Facebook Photos By Mouse-Overing Them [link]
FB Photo Zoom is the Chrome extension that truly saves you time when viewing photo streams on Facebook. With this free Chrome add-on, you'll find it much quicker to interact with Facebook photos: you just have to mouse over those photos. In other words, you just have to position your cursor on top of any photo in your feeds, then wait a second until the full-sized version of the image appears.
For non-Chrome users, you may want to checkout Thumbnail Zoom for Firefox. As with the former, this add-on shows a floating panel with the full size of a thumbnail when hovering over an image or thumbnail. Other than Facebook, Thumbnail Zoom supports Twitter, MySpace, Amazon, Picasa, Flickr, LinkedIn, Hi5, Twitpic, deviantART, PhotoBucket, Tagged, Last.fm, Wikipedia, YouTube, DailyMile, IMDb, Imgur, Photosight.ru and Google Images.
How do you find these image enlarger add-ons useful? Share your thoughts in the comments below.