An article on prototyping UI interactions.

A good slide deck.

An iPad wireframing and mockup app.

A bookmarklet that converts a page to a wireframe. Very useful for future classes.

One bazillion wireframing links.

The classic.

Wireframe Tumblog. Nice source of inspiration.

Keynote files, etc. The video is convincing.

Wireframing resources

...a really well done intro to using drawing to communicate...in comic form.

A video on Wireframing interaction in design.

Packages concept screens and control schemes that run live on the iPhone. It allows you to experience your concept without the expense of development. Each brief is simply a .plist that references images.

Also could be use for elevator pitches, notes, and interactive books. Open source on GitHub

Build simple sitemap wireframes with just a few <ul>s.