No, this would be a custom application, but if you want to really learn how to manipulate MODx (since it really is a framework system) and add modules and work with third-party application plugins, I would suggest starting with thouroughly learning to use PHP to talk to MySQL (or any other sql-based database system).
Just as an example, I recently wrote a plugin (which intercepts the document parser and adds it own functionality) to maintain a simple page hit counter. It sets up a new table in the database, with the document ID field set to UNIQUE, then uses a query to insert the document ID and a count of 1 if the document isn’t listed yet, and merely adds 1 to the existing count if the document is already listed:
INSERT INTO ".$table_prefix."page_hit_counter (page_id, page_count) VALUES ($modx->documentIdentifier, 1)
ON DUPLICATE KEY UPDATE page_count=page_count+1
If you can get around in the database, you can make MODx do absolutely anything you want.