This is primarily a reminder for myself. If you're not authenticating against a database or network directory store, your web app may need to just authenticate against a standard Linux password file.
Creating one is easy:
htpasswd -c [filename] [username]
After prompting you for the desired password for this user, it will create the file (or wipe it out if it exists), and insert the user with the password, naturally encrypted.
Go without the -c parameter to add additional users to an existing password file. Finally, use a -d parameter to delete a certain user from a password file.