Scanning directories for new files?

[Matty Sarro]

Hey everyone.
I'm in the midst of writing a parser to clean up incoming files,
remove extra data that isn't needed, normalize some values, etc. The
base files will be uploaded via FTP.
How does one go about scanning a directory for new files? For now
we're looking to run it as a cron job but eventually would like to
move away from that into making it a service running in the
background.