Because there are so many schools teaching Spanish, and so many students wanting to learn Spanish, advertisers are prepared to pay a higher cost per click (CPC) to get their ad to the top of the paid search results, or onto the best websites that talk about learning Spanish.
Check out my screenshot from Google's AdWords Keyword Tool;

Learn Spanish Keywords for AdSense
I'm based in Europe so the CPC I see are in Euros or US dollars, and at todays exchange rates that means the top result in Google's Keyword Tool is the same as nearly US$6 per click. If advertisers are prepared to pay that, imagine how you could make money online from being an AdSense publisher.
Typically Google pays AdSense publishers between 10-30% of the CPC, most publishers get around 10% if they have a reasonable website but a lot get more than that. A reasonable website in this instance would be one with good content, perhaps a blog that has short dialogs, or Spanish verb conjugations.
Learning Spanish doesn't have a great number of monthly searches and competition is stiff, but a passionate webmaster who is determined to build a good Learn Spanish website could easily build traffic and make money online from other people wanting to learn Spanish.
How would you go about building a Learn Spanish website and making money from it? Well I don't believe you'd need to worry too much about writing great content, typically the person reading your site isn't going to be interested in your thoughts, they're only interested in lists of vocabulary, verb conjugations, pictures of Spain or other Spanish speaking nations, lists of resources where they can study Spanish.
A website like this could be created easily, then after a month of building content and getting some backlinks including submitting articles, put your AdSense on the site and start to watch your earnings get counted every day. Make sure you read my AdSense ebook comparison.
I know I talk about making money online being easy, and it is, and I know when I talk doing keyword research you probably think that's easy as well, after all it's only a matter of brainstorming ideas and seeing which ones advertisers are prepared to pay well for. The next step is more difficult though, finding out if you can compete for the keyword.
Knowing that advertisers will pay to have their ad displayed on your website, and then getting enough targeted traffic to make it worth your while are two different things. With a global monthly search of 3600 for "learn spanish spain" you could probably make a couple of hundred dollars a month from AdSense if you could get to the first page of the search results.
Of course I'm not going to tell you how to do that in this article, instead I'd recommend reading Nomad's Guide to Make Money Online, a great AdSense ebook



Warren Davies said,
Sunday, January 10. 2010 at 18:34 (Reply)
Thanks for the post! In an amazing twist of fate, I am planning to learn Spanish and I totally get what you say: "I now look for opportunities to make money from everything I do"!
So I'm going to give this a shot - I had no idea that the CPC was so high.
Quick question though if you don't mind - you imply here that it's best to set up numerous sites and build a network. I'm planning a broader site that learning Spanish would fit into (a language acquisition section of a brain fitness/learning site).
From the point of view of making money, do you think it's better to set up a separate one just for the Spanish site, or include it as a sub-section of the larger site?
Cheers again for the post,
Warren
Carl said,
Tuesday, January 12. 2010 at 18:37 (Reply)
Generally I'd consider setting up a second site about language. The two niches are somewhat related, but are sufficiently far apart that you might end up with irrelevant advertising because the Google AdSense crawler will struggle to find a perfect match.
This of course could mean your earnings don't increase as rapidly as they would through natural growth of your main niche. Puttig languages into a separate site gives advertisers in that niche a clear idea of your goals, thus you might atract good advertising.
Warren Davies said,
Friday, January 15. 2010 at 15:24 (Reply)
Warren