One of my favorite little features we did in Windows Phone 7 in the photos experience was what we call “filmstrip” view. Normally you’re in what we call Single Photo Viewer (SPV), where you see one photo at a time – for example here is my kids, can you tell they’re siblings from this picture?
(For the record, I love how uncluttered the SPV is… one of the design principles for the release that we really took to heart was “content, not chrome” and we spent a lot of time working through how to provide functionality to the user without cluttering up the UI with buttons, which is how we ultimately landed on the “…” menu expansion but the menu is transparent until you tap on it so that as you scroll through images you can focus on viewing the image (the “content” of this particular experience), not the chrome. It may seem like an obvious solution now, but it wasn’t when we started 
)
You can of course swipe one-by-one to get to the next or previous photo, but to quickly scroll through multiple photos, pinch out (aka the opposite of what you’d do to zoom in to the photo) and you’ll go into what we call “filmstrip view”:
Note that filmstrip view only works on photos on your phone, not online albums or cached versions of online photos– we originally tried to make that work but it required so much back-and-forth on the network that it used up data which costs $$, and also didn’t provide a great experience (you would frequently see gray boxes as the images rendered in).
Another interesting tip: If you start from the camera viewfinder, swipe back and then pinch out and look at filmstrip view, the viewfinder’s still “in” the view – so you can quickly get back to your camera.
