The charity I work for: Teach Learn Grow (TLG) has been a long term customer of Adobe FormsCentral and EchoSign, both are really great products. Is there a way to link the responses from FC to an SQL database? If not we are going to have to abandon Adobe FormsCentral for a new forms system.
At this time there is not a way to link responses to an SQL database. It is something you might want to add as a Feature Idea in the ideas page: http://forums.adobe.com/community/formscentral?view=idea
What you can do now is export data from FormsCentral and import into any database you prefer. Here is a video about exporting to Excel or CSV: http://tv.adobe.com/watch/acrobat-xi-tips-tricks/how-to-export-form-data-from-formscentral /