Theres an api to get the posted data to an xform on the xform class called getposteddata

http://world.episerver.com/documentation/class-library/?documentId=cms/7/4b95251f-449b-6e6c-ecb5-2aa7f7e3f8d6

You can use that to render results on a template that you lock to a group. I have a client who has it that way and displays result in a tabular form. Excel export is another way if its a rare occurence