In my opinion [on getting a third season produced], it is all about the proffit/income/cash like buisness usualy is. Big-O is like an art house film - it will get lots of critical acclaim. That doesn't neccesarily mean it is going to make money. Ratings were high for the second series (Adult Swim said that the rattings were low but the fandom says the oppisite) but the DVD sales - like how Kim Manning mentioned that Jason DeMarco said - "were middling". This is not surprising since ratings in Japan were less than what they are in America. Also, lots of reports of bootleg sets were said to have been made - injuring profit reapings. The only way I can realistically see even consideration for a season three to come back is if sales on merchandise sky rocket.
I suggest that if you want a third season, buy the DVDs, get the new $200 chogokin figure, get the mangas, even import the "Paradigm Noise" novella. Plus - and I am going to start doing this - start watching Big-O when ever it comes on which as we see is comming on at 4:30. And hell, get the Big-O related forums on fire. Atleast we still got commercial apperances, like the Adult Swim spot refrencing that since Japan has the live sized Gundam and Tetsuijin-28 (Gigantor), we should make a 1:1 Big-O. That was humorous.
But there is a delima of people being unwilling to buy merchandise. Let me quote "EricDent" who posts on the Atari Godzilla forums and the Anime News Network forums, "there is a whole generation of so-called "fans" that have never bought a single DVD copy of any anime show, their mentality is that if they can see it free, then why buy." So alot of you who haven't bought the DVDs need to. It is nice that the episodes are on the official Adult Swim website and it is nice that every couple of months [AS] shows re-runs of season two, but you need to buy the DVDs. The economy is bad, but come on.
So, the question is what do we buy and where do we buy it? The DVDs are a big thing for people to buy. Do not buy off an auction site. Sure, they are good at low prices but bootlegs are omnipresent and companese such as Bandai do not look at the sales stats on auction sites (save the EbayStores sites). This is due to people auctioning off their items are not going to restock them with an order from the company that makes the item. Amazon is a good place to buy. DVDEmpire and other sites like those are good ideas. Another good item to buy is the new Chogokin Big-O that just came out. They are not going to be released until Christmas time comes around so pre-order numbers are important. Again, auction sites would be a frowned upon but if you must, atleast most of the people selling it on the auction sites are Store sites.
There is some other merchandise which some should consider buying - but not without some background information researched first. If you do not have a collection of memorabilia built up yet, you want to buy the stuff that is still being produced. Merchandise no longer being produced are not studdied upon by the companese that produce the items. Theres coin figures, mangas, soundtracks, and alot of other merchandise which some should get, but DVDs and current merchandise is what you should shoot for.
NOTE: These are just the hypothesis of the author. The author wishes you to do no such actions like said in the article above - but rather just advice in the goal to get a season three of the anime, "The Big-O".