(Note: Have a look at our CADminTools package - including a user database, license tracker, etc...)
If you're looking after a large group of CAD users, some kind of user records are vital. Unless you have a really good memory, you'll need somewhere to store information about your people, including:
username, computer name, product they work with, location, email address
You could store this data in a notebook, text file or spreadsheet, but a database is probably more efficient, especially when the data set grows and you need to search, filter and re-use information.
For instance, say you're planning an update to your CAD software and you need to copy files to all users. It would be handy to have a current list of all computers that are using CAD. Then you could use this list as an input to a batch script that copies files out to clients.
Or, say you need to send email to CAD users in a particular division, advising them of changes to your filing system. Again, it would be handy to have a current list of CAD users that you could filter by location and extract email addresses.
Make life easier for yourself - store user data in an easily accessible format. You could also integrate the data with other functions - use your imagination!
(PS: As with any other database - remember to backup regularly.)
I used to keep track of users with a simple Access database. Then I wondered, "what if you could work with this data in a browser...?" After experimenting with ASP pages, I came up with this new tool: the Web-enabled CAD User Database.

The tool lets you maintain your user lists through a browser. You can quickly add or edit details of a users location, the products they design, their computer name, email address & CAD usage. You can filter the users by location or product, or sort by email, etc... Then you can list the computer names for upgrading or get a list of email addresses for bulletins.
Here are some steps to implement this tool: