Just an idea, charge for the API. I can easily imagine this being very useful for a feed/content provider to automatically source an automatic image related to a news feed/ or product.
I do like that idea. Being bootstrapped I needed to be a bit more direct with getting revenue from the majority of the traffic visiting us in the short term.
What do you think of our very lightweight freemium model? (Searching for dog or cat is free, other searches are behind the pay wall.)
That's not freemium. It's a demo. With true freemium, someone can use your service regularly while on the free plan. Very few people are going to use your service just to find dogs and cats.
Not saying you shouldn't keep it (you should. demos are a great way to get people to convert), but it's not freemium.
I think the best freemium model which with my previous comment would be to pick about 10 "dynamic" topics, along the lines of say todays current google trends http://www.google.com/trends/hottrends
which would give people enough of an indication of the utility of your site.
What do you think of our very lightweight freemium model? (Searching for dog or cat is free, other searches are behind the pay wall.)