The reference plugins are provided by the Maliit project in the plugins repository.
3rd party Plugins
These plugins are not distributed with the Maliit releases, but they can be used with Maliit.
Sailfish Virtual Keyboard
This plugins might not be from much direct use anymore. But they might help to create features for current plugins.
The keyboard used in the Nokia N9 and Nokia 950. It requires libmeegotouch. It can be extended to support new languages through input method engines and layout files.
Cute Input Method
Maliit Plugin JP