Good example for a touchscreen-optimized tag input field?

Entering tags in a text input field is a common task. Most of those fields use some kind of JavaScript-based suggestion. How would you optimize such a field for use on small, touchscreen-enabled device? For the iPhone, I would set the autocorrectand autocapitalize attributes to off and try to make the tag suggestions bigger. But what's the "best" solution to place them? Do you have any examples of web sites where tagging on a touchscreen device is solved in a good way? Any libraries that support this?