Many apps are now providing a customisable row of keys above the main keyboard - for example Textastic, Nebulous Notes, ... I will be investigating doing something similar for Trunk Notes in the near future.
That is one of the most wanted features in Trunk Notes - IMHO! The Textastic App (http://www.textasticapp.com/) has a very nice way of implementing cursor movement, mark text etc. Other apps too - eg. Byword, Day One etc.