Several “iPhone simulators” have been published on the Web, lately, that claim aiding web developers in creating iPhone-compatible web applications. Beware of them! Aside from a bunch of other issues, they do not display text and graphics the same way (size, proportion, layout) that iPhone does so you may fall in false confidence and when people do actually open your page in iPhone it will look freakish - neither like a normal site, nor iPhone-optimized.

I will list two of the most populart ones, here