You can make a custom report (or use a canned report, if one of the built-in reports meets your needs) and then either manually use the Export to Excel/Export to CSV functionality on the report (click the report, and the options appear when you click the lightning bolt) or set up the report to occur on a schedule (can be set up under Admin - Reports - Report Schedule List). Scheduled report results can be created as files or sent as emails in either an Excel, CSV, or HTML format.
If you're using the schedule option, you might be able to setup an automatic process: make a monitoring workflow that either checks a file location (or monitors a mailbox), and then parses the data and enters into your system (if your system has an API that workflow can work with)