Hi all! I think my question is fairly basic, but I would like a clarification: in the Pricing part of AWS we can see that Amazon charges people around .10 by the 'instance computing hour'.

I've seen in a blog post somewhere (can't remember where exactly, and even if I did I think it was in Portuguese anyway) that this way your minimum monthly payment would be $72 (= .10 $s/hour x 24 hours x 30 days). Is this correct? (I don't think it is!)

In my understanding is that this 'virtual computing time' is only used when your machine is actually doing something (serving pages, serving the admin via ssh, whatever), so real billable usage would be less than 720 hours/month in most webserver scenarios. Is my view correct?

If it is, then it leads me to another question: is it economically interesting to buy access to one of these instances for testing? I mean, would I have the 'freedom' to 'forget' about it for a month and receive a very-close-to-zero (as in, a few cents) bill? Do you do it/know of anybody who does? Any thoughts on the matter (as in, "yes, it's a good idea", or "yes, but there's this 'gotcha': ...", or "no, nobody does it because of...")?

PS: sorry for the loong question text. I highlighted the main questions for easy view. Also, I'm not sure if this question is actually more than one and if it's desirable for the community, so, sorry if it is too!

Thanks in advance!