I haven't seen this mentioned, so I thought I could put a word about it : I've recently started using MessageEase from
Exideas as an alternative to the classical input methods. MessageEase uses an interesting input method, which lets you access every letter/number/symbol and even some functionalities (Copy/Paste) from a single virtual keyboard with large keys, using a drag and drop interface.
While it requires some time to get used to, the interface is actually very well thought, and I can only advise everyone to at least check the demo version.