If this has been discussed before, I apologize in advance.
I was looking around yesterday for a mobile emulator to check out my sites with as I don't have all the latest greatest gadgets to play with.
Found out that there is an emulator built right into chrome that works pretty well from what I can see. It emulates the screen size and user agent for a lot of the various mobile devices available.
To get to it:
1. go to the chrome settings dropdown menu and select tools and then developer tools.
2. In the developer tools there is a tab for emulation, select it.
3. If you don't have the page you want to work on open yet, Then open it.
4. There is a drop down box with a bunch of different emulations you can pick from. Choose the emulation you want.
5. Hit the emulate button below the drop down.
6. You are now looking at the page as chrome thinks it will appear in that particular device.
7. When done, make sure to hit the reset button to return to your normal browser settings.
I compared it to an actual ipad presentation and functionality and it came a lot closer then the other ones that I had tried online. They seemed to emulate the screen well but did not seem to pick up on responsiveness at all, chrome loaded the proper styles etc.
So, I hope this helps.