In addition to above - On a Mac if the View is set to icons ( and best to large icons) then you can browse your raw files in the finder. You can also select a number of them and Control Click to open with the Preview app. This is really useful.
Indeed it's even easier (and faster) than that. With a file selected in the Finder, just hit the space bar. This will bring a "quick look" of the photo. Press the space bar again to close the quick look window. Or you can use the arrow keys to navigate through the photos while the quick look window is open and rapidly view them all. You can share files, email them, and do lots of things from within the quick look window without ever having to "open" them.
Note this works for nearly every file supported on OS X: PDFs, Word, Excel, images, sound files (yes, it will play!), etc.