2) prerelease auctions.  These are domains where the auction venue has contracted with the registrar, like Fabulous or Moniker, to auction off non-renewed domains.  Just before a domain enters the pending delete process, it goes to a private auction to any person who has backordered the name.  Some people feel that back links on these type of auctions still provide a SEO benifit. My testing indicates that there is zero SEO benifit when these domains are redirected into another site.  So if you get a domain with "pink squirels" in a lot of achor text to a domain and then point it at your domain, you don't rank for "pink squirels"

Here's a test I have in process.  I bought an old $5 closeout domain from Godaddy TDname expired auction.  I put a quick minisite up and linked to it with a crazy anchor text phrase.  The domain is ranking for that crazy term now.  It's gone through one pagerank update and I'm waiting for a second to come.  Then I'll redirect the domain to another minisite.  I suspect the second site won't rank for the anhor text, but we'll see.  
When you see one that looks pretty good you can just click on the bid button and you’ll be taken to Go Daddy Auctions which shows some more information about the domain bidding process, how many people have bid, the traffic potential per month, the price which is now $12. How much time is left? You can make a bid. It’s based on the link profile and it’s relevancy, authority and your budget. This domain looks like a good bet for you.
Before you park any domain names, you must focus on finding hot keywords that buyers would be interested in. The best way to make sure you get a good return on your investment is to pick a domain name with acceptable traffic, somewhere around 10,000 searches a month. You can do this conveniently by using tools like Google Keyword Planner or Niche Finder Software.
Most of the website owners interested in an expired domain that has existing traffic, backlink and good SEO metrics. This kind of domain more likely gets buyer easily since it has a plus value for search engine optimization purpose. You can find high-quality expired domains that have SEO metrics by using BuycomDomain - The Expired Domain Search Tool for free, as seen in the picture below.
Buying and selling domain names is an exciting adventure that for some seems to conjure up images of finding hidden pirate treasure or guessing the winning combination on the next Powerball. Stories abound of domains that were purchased for $8 dollars 15 years ago being sold today for millions. Of course, that leads the more adventurous of us to wonder, “How can I do that?”

Building a solid domain portfolio is not a piece of cake; it may take you several months or years to achieve this goal but it will definitely be worth it in the end. When you are in the fishing phase, look at the potential of the domain name. Another common strategy used by seasoned domain flippers is to get hold of some high profile domain names and sit on them until they soar in terms of value.
The domain name industry is quite similar to the real estate industry in a lot of aspects. There are end users, brokers, consultants and domain flippers or “domainers”. Domain flipping works similarly to buying a house, renovating it (or even sometimes just sitting on it) and then selling it again at a higher price point. The gist of it is: you’re purchasing a domain name and betting it’s worth (or will be worth) more than you paid for it. If you’re right, you get a nice paycheck and move on. Those who make a living out of this just rinse, repeat, and scale.