MGTitleMenu is an open source iOS interface component that lets developers conveniently add pop-up, tile-based contextual menus to iOS apps. It makes the most sense on big screen iPad apps, but can also be used on iPhone or iPad touch. MGTileMenu, as the name hints, is from well known iOS developer Matt Gemmell under a free, attribution license (it can also be licensed without attribution for a small fee).
The idea is, if you're holding an iPad, you can invoke the context menu via a gesture (for example, a double tap). You can the quickly tap one of five action icons, or tap a "more" icon and get additional sets of action icons to choose from. MGTileMenu can also be configured for left handed or right handed use.
Gemmell was also kind enough to include his design and development process in his blog post about the component.