A comprehensive list of software applications that can be projected using an iPad 1 from a Wiki containing lots of information about pedagogical uses for iPads.

This is a system often used in commercial areas like movie theaters or shopping malls, but the theory could be applied well to the learning environment.  Here, the only specialized hardware in an infrared emitter which captures motion to enable the interactivity.  The technology handles multiple touch input.  This kind of setup could enable large scale interactive setups that one could envision being extremely useful in collaborative learning.

A youtube video describing a method to remote-control a PC running the SmartBoard NoteBook software.  Another stop-gap measure between first-gen and second-gen systems.

Details a couple of different ways to use a first-generation system (SmartBoard) with next generation mobile tablet devices.  These are two interesting ways of bridging the gap between the two types of systems, if for instance, your institution has already invested in SmartBoards, but you also have access to a tablet device.  Includes links to software.

Software for collaboration that can be used by multiple people simultaneously and projected through an interactive system.  Uses "virtual sticky notes" and real-time collaboration.

Mimio Teach interactive whiteboard system product page.  Mimio is a good alternative for institutions who require a less-expensive solution.  These devices attach to existing (regular) whiteboards to create an interactive surface that interfaces with a computer via a Bluetooth adapter.  These devices are good for low-cost deployments and situations where the device must be shared by multiple locations.

SmartBoard brand product line.  Displays 8 different models with various features including 4:3 dimensions, widescreen boards, and all-in-one systems that include built in short-throw projectors.