Are there any Web sites that simulate the appearance of a Web site on a mobile device?

Google has just revised its page rank system to take into consideration mobile devices. I would like to see if I can modify my Web page to make it friendlier for mobile devices, though I am not sure if that is possible. For anyone who cares to look at it, I have a high school level math education site. It would be helpful if there was a site that I could bring up on my PC that would show what the site looks like from a mobile phone.