Lockdown is a simple plug-in that solves a vexing problem.. How to easily 'secure' a web page.
Note this does not work on .mac, it requires a web host that uses Apache & PHP and even then it may not work. Please download the free version and test it before buying! (see here for instructions on how to test without purchasing)
GoDaddy users look at the FAQ
Using this plug is really quite simple, simply install the plugin and add a 'Lockdown' page. Go to the 'Passwords' tab and add a password prompt, users and select 'password protect this page' (you may also optionally enter a date this password should expire as well as a web page to send each user to)
On the 'Page' tab you have a full styled text page that you can put your secure information in. You can also optionally redirect the user to another page (say you want to keep your flickr photos secure, you can put a 'rapidflickr' page below the 'Lockdown' page and redirect the top level page to your flickr photos)
Testing -- IMPORTANT
Once you have a page you need to test it to verify that your hosting company supports locking down a page. I recommend creating a 'dummy' website with perhaps two pages, one that is locked down and one that is not. "Publish" your 'Dummy' site and then visit it. Your Lockdown pages aren't secure until you visit it at least once (this is necessary to configure your server correctly). The very first time you visit a locked down page it will configure your account, if it's successful it'll tell you.
Now hit the 'refresh' button on your browser. If everything is working you should see a password prompt
(In some cases it won't be able to configure and will give you an alternate approach. Please follow the instructions provided at that point)
If you see the above then that page (and all pages below it) are Password Protected! Note that you only need to do this configuration step once. After it's been done once it'll remain locked down (even if you add or change content or add or change usernames & passwords!)
If you ever want to 'un password protect' the page simple uncheck the 'Password Protect' button, republish the page, visit the page to reconfigure and it's now no longer password protected!
The 'On Pageview, Send Email' is great fun if you want real time stats of what's going on with your page... You don't even need to lock a page down witha password for this feature to work! Be warned that if you have a popular page you will get a lot of email!