Many times on groups and forums people were asking about script which will populate AD with data from Excel file. Alex Tcherniakhovski has modified one of scripts available in script center to create test data in AD environment based on Excel files. This script was created for testing pourposes but it can be used and easily modified to create real users data in AD.
And regarding creation of test data in a quick way for AD testing pourposes – new version of joe's ADMOD will rock 🙂