I've written a set of scripts that perform/automate the monthly billing cycle for a large agency. The system inputs are quite diverse and definitely need the sort of glue that Perl provides.

Inputs include:

1. Printer log files from Solaris printer servers
2. Printer log files from a proprietary Win2K3 printer server
3. Log files from IBM mainframe servers
4. A proprietary data collection application utilizing a MSSQL Server database
5. A manually maintained MS Access database containing > 20000 records

Since manual inputs are a big part of the system, it is important to validate that all data meets specified criteria and is complete.

I also generate logfiles and exception reports to support manual review/update of faulty data.