ToDE - tODE - the Object centric Development Environment. A bit stagnant in development, but still interesting: an IDE that builds on Pharo Smalltalk. The special feature: it runs in the browser, but offers all the usual Smalltalk development tools there. In principle, you could therefore install a hosted Smalltalk image as a development environment for the iPad and play with it on the go (Pharo and Squeak fit well into the browser interface because they usually don't come as native Windows, but as Windows-in-Windows - and here simply Windows-in-browser).