There's a few key things you can do to constantly check your email and make sure you know when the beta key comes. Let's take a look at them.
That's the magic refresh key. It works on all browsers, and is a throwback to the old days of computers.
Press Control-R or Apple-R
Does the same thing as F5.
Auto check your email every minute
Most email programs allow you to "grab" email off the server as often as every minute. This is how I have my clients setup, and it will more or less let you know as soon as you get an email.
Have email alerts enabled
If you're at work and using Outlook, which I know many of you are, be sure that you've enabled alerts to pop up. The same goes for other programs and email services like MSN, AOL, etc... If you have a gmail account, you can get alerts via the Google Sidebar. The Google Toolbar, which I use, can also be configured to display a notification icon. However that is much smaller and less noticeable.
Make a special alert for email@example.com
You can setup most email program to alert you in some special way when an email arrives from a particular email address. Usually you can have the computer play a sound. I do this with some folks that I want to get back to right away. For the beta, setup firstname.lastname@example.org to play some sound. I recommend the red alert sound from Star Trek. You'll have to use your own googling powers to get it though.
Check your junk mail folder
Either check your junk mail folder or add email@example.com to your safe email list. Often times email clients will send mail from the firstname.lastname@example.org address to your junk folder. I know this is the case with Hotmail, for example. Do yourself a favor and make sure this doesn't happen to you, or if you can't avoid it, start checking the Junk folder as well.
Hopefully with the above methods you'll know as soon as you get into the beta, and then you can begin the long wait as you download the 2 gig patch file. Good luck!