The iOS system isn't really useful for writing programs on the device mostly due to the filesystem being weirdly off limits to apps. But in the past I've used a

The iOS system isn't really useful for writing programs on the device mostly due to the filesystem being weirdly off limits to apps. But in the past I've used an iPad to SSH into servers where I happily wrote code. And now that they support cmd-tab, it will be even easier. If there was mouse support it could conceivably replace my laptop (especially if I ever embraced web based IDE's).