As I understand you used alexa as an indicator of the traffic - am I right?
Here is what you need to have in mind when choosing typos with the help of alexa. When you find a popular website with good alexa rank, you then need to know if it's traffic is typein or link generated. A good indicator in this case is the overture, so use it in combination with alexa.
mapquest.com is one of the most popular US sites, and mapquest.org had a january ovt of 710 - so I guess this indicates why your typo is receiving traffic
Now take the websites you used to register the ones you have here for appraisal. Eventhough they rank well in alexa, they have no ovt, which indicates that eventhough they have high traffic, they do not have many type-ins thus registering their typos is most likely(but not necessarily) a waste of money. But you can always taste them and drop them right?
The only one that might receive light traffic in my opinion is callme911.net , only because callme911.com had some ovt in the mid xx range back in march
orientbeachonline.net might also get some traffic now on second look