Viewport resizer

There are several bookmarklets out there that can do a simple change of your viewport to match the size of common mobile devices, but I’ve never seen it in as slick a package as what Viewport Resizer offers. You can customize the bookmarket to only include the viewport sizes you chose and jump between portrait and landscape views with a single click. It works great on local development files and, while I haven’t directly tested it, is touch friendly as well.