Ask HN: Collection of UI Examples?

I'm tasked with showing a group of business folk what is possible on the web, prior to a day-long design/brainstorming session for a major app.

The idea is to assist them to break them out of the box, showing them all the possibilities of a Web UI, so that they can be more free in their brainstorming, and not just ask for the standard leftnav and forms.

So the question is -- does anyone have a collection of sites that could be used to demo different UI concepts?

If not a collection, even just recommendations on creative, but effective UIs would be of great assistance.

Edit: This could include all components of an app -- Navigation, Forms, Data Views, Reporting, Widgets/Controls, etc...