Hi
My suggestion and just an overview :)
1
Create a list of the alphabet in db either as free table or a list of tags etc.
Store in each entry A, then B etc
2
Create a search & list of these letters
3
In the search view add a search & list field
This will be passed the value from the list item ie A, or B
4
The Search & list field will lists all users that begin with the passed value
That will require some funky sql query...
create-a-dynamic-list-within-a-list-item