HippoRemote

HippoRemote is an iPhone/iPod Touch app that turns your mobile device into a wireless keyboard and touchpad for a networked computer. The free Lite version provides the basic keyboard and mouse functionality while the paid Pro version adds custom interfaces and macros for different programs alongside extra plugins to minimize the need to switch apps.

HippoRemote uses a client-server system, meaning you not only need to download the app itself, but also need to install a piece of software on the controlled computer so that HippoRemote can connect. Any VNC server software will work, but some of the more advanced features require the use of HippoRemote's custom VNC server. The touchpad itself is quite functional offering advancements such as multitouch, and circular scrolling. The Pro version comes with custom interfaces that let you control popular programs such as Boxee in a more intuitive fashion.