The Cornell College of Ornithology puts out a list of binoculars and their rankings. It isn't every year, but it's a good list. Bird watchers are an ideal group to get advice from as their binocular use is more intense than most others.
Taliv is right about the small increases in performance related to price. My Nikon Monarchs (8x42) were highly-rated by Cornell are not as good as my Swaros, but the differences are so very minor that I will never buy the top tier again. The quality middle-range is the sweet-spot in binoculars. They are vastly better than the $100 roofs you can get whilst the top ends are not vastly better than the mid-ranges.
You don't get what you pay for on the top end. Yes, they are very high quality -outstanding quality. Yes, it is noticeable. Yes, I own both types. But my Swaros are not more than 3 times as good as my Nikons. When on the water in my kayak, I have a Nikon. When at the farm, I carry the Swarovski.
Between $200 and $400 you can get some outstanding roof-prism binoculars. In my experience, Leupold is not the best to go to in this range as there are better binocs for the price.
Porro prism binocs are poo-poo'd by many, but for high quality porros you pay much less than roofs. Leupold Yosomite's and Nikon Action Extremes are excellent binoculars (porros tend to give better 3d images than roofs and better color for the price). I bought my mom a pair of Nikon Action Extremes for back-porch bird watching years ago and am constantly impressed by their quality.
But if you REALLY want good info, check out the birders and their equipment:
http://www.birdforum.net/forumdisplay.php?f=112