Emulators
iPhoneTester
iPhoneTester is an online iPhone simulator to test your iPhone specific web applications. The beauty of this is that you can test in any browser, although they do suggest you use the Safari browser (which makes sense).
Platforms: Any, but best viewed with Apple’s Safari browser
Link: iPhoneTester
iPhoney

Market Circle has release iPhoney, an iPhone emulator that runs on the Apple Mac OS X (10.4.7 or higher).
For those of us developing iPhone web apps the iPhoney emulator could be just what we are looking for. It is a small application that simulates browsing on an iPhone. It uses a 320 x 480 view to test your web apps and although it doesn’t have all the fancy touch capabilities i.e. scaling or zooming in and out, it does allow you to rotate the page just as you can with the real iPhone. It also allows you to set the user agent to that of the iPhone.
It’s not perfect but it is free and does a pretty good job of showing you what your apps will look like on the real thing.
Platform: Apple Mac OS X (10.4.7 or above)
Links: iPhoney web site