iPhone touching and gesturing
Really interesting article here on some of the things you can achieve with HTML and JavaScript for iPhone's Safari browser. I'm an iPhone n00b but am impressed so far with the device (which'll be even better once O2 enable the "phone" part and connect me by midnight tonight apparently). Being able to develop iPhone-specific web content interests me and it seems you're able to work with screen interaction quite a bit.
Direct link to the demo here, but won't work properly unless you're viewing with an iPhone/iPod Touch.