The IP popularity and domain popularity each play a part in the overall quality evaluation. If you come across an expired domain with a high link popularity (i.e. a large number of backlinks), but then poor values when it comes to IP and domain popularity, you can assume that these links were obtained in an artificial way. Domains like these will have already caught the search engines’ attention. Perhaps this is the reason why the domain was abandoned. Users that want to start a serious online project should steer clear of these domains.
The truth is that you require at least one year’s time to get around only the basics of the domain flipping business, leave alone making huge money from it. During this time, you’ll make several mistakes, buy useless domain names, lose out prospective deals and much more. Domain flipping is far from any get rich quick method. If overnight results are what you’re after, domain investing may not be your piece of cake. This business involves a real and steep learning curve which many people find difficult to climb.
Yes! Selling domain is an emerging trade and no wonder if it can develop into an exchange. www.DomainX.org has been initiated with this view. There are some good ideas in the comments regarding which names to buy and how to grow their value. However one must not forget that it also involves a recurring cost (annual renewal) and keeping many of them might become difficult if you are not really selling at least a few to cover it. Enjoy free listing at DomainX.org.
Many non-savvy internet users may not even be aware of the existence of other extensions. That said, because there are many new extensions popping up every now and then, you can often find amazing one word and 3-letter domain names with these new extensions that are otherwise almost impossible to find unregistered in the .com world. Additionally, these new extensions are becoming more and more familiar to users every day, hence it's almost certain that their value will continue to increase as time passes and wider adoption manifests.