advice re: creating a new profile fieldtype ( multiselect, multiple choice, with "Other" text box options)

By Tom Cal

As an Ellgg Administrator, I want a profile fieldtype that is well suited for asking multiselect, multiple choice questions, with "Other" text box options.  

Users can select zero or more responses from a list of 100 possible options, and users will also have an option to fill in several "Other" text box fields.

I want the user interface to be both desktop and "mobile devcie" friendly.

What user interface do you suggest? Scrollboxes? Checkboxes? 

If using a scrollbox, what is a good desktop and mobile device friendly way to offer users the ability to select more than one response?

Please provide advice and insights on how to proceed. Does anything like this already exist, either within Elgg, or for demonstration purposes, elsewhere?

Thank you!