has anyone ever integrated Crystal Reports into an Access application?

no, but you might want to try here
http://www.tek-tips.com/

they have a crystal reports forum there

What would be the purpose of using Crystal Reports within Access. The report structure within Access is strong. Crystal Reports is used as an add-on to programs that require a separate report writer, such as financial, visual basic, etc. (People use to use Caret Reports, which I found to be more user friendly, but Crystal has now become the norm) However, if you are trying to integrate Access information into another program to write a report from Crystal, then it can be done by exporting from Access into the other program. Hope this gives you some insight.

you can use tables from access as recordsource of your crystal report via ODBC. check Control Panel >> ODBC >> USER DSN. choose your driver (MS Access), follow the procedure, therafter.