Responsinator is a wonderful tool to quickly check whether your website’s design is responsive or not.
For eg. My present website is not responsive => http://www.responsinator.com/?url=www.humbug.in
However a theme I blogged about few days back => Reverie has a fully responsive website => http://www.responsinator.com/?url=http://themefortress.com/reverie/
I’m try to create a whild theme for the Roots theme on my test installation and I can see that I have made a mess out of it => http://www.responsinator.com/?url=testwp.humbug.in. However it iss still better than the present design for my site which isn’t responsive at all.