A simple user importer plugin. It expects a CSV file with three columns.
- user name
- email address
- password
Here's a sample: https://docs.google.com/spreadsheet/ccc?key=0AqnIEx5v8_AGdFBTbk5xSDZrdzlVWXNBbGplRWZCckE&usp=sharing
Export that as a CSV, and it will work with this importer.