When a tag is used in a HTML page, is there a way to style the text size in
the scroll wheel that shows on the iPhone?
We investigated and couldn't find any reliable way of altering the display so we looked into different libraries. We're having good luck with the Mobiscroll library for jQuery. It is a more up to date project than the cubiq project referred to in other responses.
The control is themable. You can easily change the appearance of if in CSS. It also comes with pre-defined, nice looking color schemes.
We chose it because it works across devices allowing for a more consistent look & feel.