I've recently discovered Textastic for coding on to go. Something I would like to see (as a PHP purist) in future releases are database table autocompletes. As a developer working on various projects at the same time, I often get confused as to which table belongs to which project. 

If I had the ability to specify a remote DB connection and have table names autocompleted (a local cached list might be a good idea) when writing SQL queries, that would really boost my productivity as I would no longer need to hop between apps. 

Just started using textastic and it really is a great app, with well thought out and beautifully implemented features.  The one thing it is missing which makes it unsuitable for anything other than small projects or minor edits is the inability to define and then use macros by recording a sequence of keystrokes/searches/etc and then allowing these to be repeated by selecting the macro.  Even the ability to define a single macro quickly in this way can help speed things up, and the ability to save a few can transform the editing experience.

Margin settings would make Textastic for IPad into an excellent general purpose editor. Currently, the text lines are too long for ease of editing an essay. My hack is to set Inconsolita for 30 pt, and zoom in to get margins and readable  text. Also, margins leave space to leave the navigation wheel up.