This idea is laugh out loud funny, I fell out of my seat, but a great idea and very creative. If I ever hire a staff I'm going to hire you to lead my creative team.I see a couple of things, you could make it a SEO site that approaches & teaches the idea by using a parable of farming.
You can have the site look like a field and just as you would show someone how to plant corn or tomatoes you can show them how seo works.
1. this is the seed
2. this is how you plant it
3. this is what makes if grow
4. look what happens to it in bad weather
5. If you don't feed it original content, such and such happens
6. If you plant in the direction of the sun, you'll get first page listings..
ect..ect..
Or the same thing can be done but make it an interactive game, where people take their site and apply the "farming seo technique" to see how their crops grow. Maybe they win little prizes. Learning Seo in an interactive gaming type of way may be fun.
That's my thought when I saw it....
*the exceptional businesses of our esteemed moderators