I recently got the domain name watchingthewatchers.com in a drop when the previous owner let it expire. Since Watching the Watchers has been published at the same name in .org since 2004, we've been losing traffic from people who mistakenly tried the .com and ended up at a parked domain.
To get the domain, I set up an account on GoDaddy and used its domain monitoring and back order service. You can monitor 100 domains for $5.99 and receive email when they're put on hold for non-payment or their status changes in other ways.
You can backorder a specific domain for $18.99 or five domains for $94.95. This doesn't guarantee you'll get them, because GoDaddy's competing with other domain-drop services and registrars, but if it fails you can reassign your order to another domain at no cost. Based on a few times I tried it out, it appears that GoDaddy loses more often than it wins when the domain's hotly contested. For this particular domain, I felt like I had a good chance because the old owner used GoDaddy as his registrar.
GoDaddy only will sell a backorder for a domain to one customer, so if you wait for the monitoring service to tell you its on hold, you might be too late.
The only disadvantage to using the service is that it increases the likelihood you'll accumulate more dumb domains you had no rational reason to register, which has been an issue for me. I also got sins.biz using GoDaddy's drop service, but all of the decent ecommerce possibilities for that domain are illegal in the U.S. outside of a few counties in Nevada.
