It's easy! Have many many users in your channel and want to keep track of how many are there? You can make life easy for yourself by generating the User List report under Analytics.
The user list gives information about the user, their email id, and their title within the channel. It also provides information whether the user is an author in the channel and also gives details about the role of the user in the channel.
Also, additional information appears when you hover over the user.
Here when you hover, the create date, language, and zip is shown.
Apart from this when you click on the 'Export' button, a drop down of more filters will appear. These filters are the extra information that you may have given while saving details about the user. You can search for users with these filters too. Select the extra filters or if you don't have any just click on the Save button (which looks like a floppy) and your excel report will be generated.
This way you can keep tabs on all your users in your channel!