Module to upload multiple users from *.txt file?

I have had a look at the modules currently available for managing users and can't seem to find one that will allow me to take an existing *.txt list of names and email addresses and use this to automatically create and delete multiple users.

Each year I will have around 500 users (students) to add and delete within the space of a week and could obviously really do with this being an automated process. The closest thing I can find is Userplus but this still requires each username and email to be entered by hand. Have I missed a module, could you develop one or could you help me to know how to tweak an existing module to make this an automated process? Thanks.