Have you considered donations? Of course this will highly depend on your site's profile and audience, but on the other hand advertisements are the web's plague. They attempt to track and distract users. I wouldn't be surprised if most of the visitors used adblock anyway.

hmmm... I haven't think about that. But I don't think it will work in my case. The idea is to make a site with lots of small tools like several conversors, calculators for different tasks, teacher's agendas, anything I can came up, in the middle of a frame of ads to create traffic and revenue. I know there's a lot like this around, but I haven't got time to implement my "big ideas" and I thought I put a small project that may create some monetization and that may grew with time. I'm also using it as a tool to learn some tecnologies I want to learn and can't use in my daily work.

Do you have some information on the level of success other sites have with donations ? My impression is that the return is almost 0.

@#54036777 For these kind of applications, I'm afraid you are right. People are likely to just search for "calculator", use the first one that fits, and go away. This is a considerably different approach than for information providing sites such as Wikipedia (some figures) and The Web Archive.

Yes... anyway, thanks for caring :) If you have any other idea now or in the future I'm more than happy to hear it.