I have used Mindmeister in class with low-level learners to create mind maps of lexis on their iPads, iPhones, and Android Phones, when brainstorming ideas for a new topic. Mindmeister creates a tidy mind map that can be saved and referred to out of class, enabling students to review new vocabulary. Learners can personalise their mind maps or create collaborative maps that they share.
With Cambridge exam classes I have encouraged students to use Mindmeister to organise their ideas when writing plans for their essays, reports, proposals, articles, and letters. We have also created a model mind map for the plans as a collaborative task using an iPad which was later shared amongst all the learners.