According to the BusinessWeek article, "Why Yahoo's Panama Won't Be Enough", Google is making an average of 20 cents per search:
Using data on total search queries, released by comScore, Caris & Co. analyst Tim Boyd estimates that Yahoo made on average between 10 cents and 11 cents per search in 2006, bringing in a total of $1.61 billion for the first nine months of the year.
Google, meanwhile, makes between 19 cents and 21 cents per search. As a result, it made an estimated $4.99 billion during the same period.
Wow, is it just me or does that seem really high? According to my Google Search History, I'm averaging about 30 searches per day. That means Google is making about $6 a day from my surfing.
[via Geeking with Greg]

Google's most expensive keywords in my experience are those for the SPAM subjects - credit repair ($8.90), Viagra ($9.11), Mortgage ($10.71), Mortgage Loans ($13.70), Gambling ($6.13), Drugs Canada ($6.90), Mortgage Rates ($13.00), Refinance ($16.70), etc...
My guess is people which look for these subjects subsidize "normal" Internet users, who typically don't click ads and therefore are basically free search users.
Although the adword keyword tool does not give a specific # for search volume for each keyword, "Credit card", "gambling", "mortgage", "poker" and "viagra" are all very close to the "maximum" side of the search volume rating bar, meaning they probably bring a very significant amount of cash to Google.
Overture search tool says there were 957,678 searches for the word "Mortgage" last month, and Google is said to have close to double the amount of search volume of Overture.
So, assuming Google has around 2,000,000 searches for "mortgage" a month, with a 2% Click thru rate on advertisements, and an average ad price of $10.71 for the keyword mortage, it looks like Google makes $428,400 / month, or $5,140,800 per year in revenue just from the keyword "mortgage".
Add on the other spam keywords and you're looking at somewhere between $50,000,000 -> $200,000,000 per year in revenue for the SPAM keywords, which helps balance out all the regular users nicely.
Posted by: Ari | December 28, 2006 at 09:18 AM
Thanks for the great comment, Ari. Interesting analysis.
Posted by: Matt | December 28, 2006 at 11:25 AM