While no substitute to testing responsive layouts on an actual device, this bookmarklet is great for initial and ongoing testing. This one is a little better than others by not only resizing, but also for sending the correct user agent and injecting the appropriate meta tags.
http://lab.maltewassermann.com/viewport-resizer/
responsivedesign
Good way of telling, and nice post to obtain information about my presentation
subject, which i am going to deliver in academy.