/csvimport

Example module for Drupal which imports a CSV file (then does nothing with it)

This is an example module for Drupal which uses file upload and Batch
API to accept a CSV file. It generates a batch and runs it; the batch
iterates through each line of the CSV (except the first) and does
... nothing.

The basic idea is that if you're writing a CSV importer for Drupal,
maybe you can start here and save a bunch of time.