Is guadagnarebitcoins a scam? I found this site: 

http://guadagnarebitcoins.altervista.org

What do you think? Is it a scam? Are the things listed on it scams?
The site covers two topics:


A basic introduction to Bitcoin
How one might be able to obtain Bitcoin for "free"


I'll discuss only item 2.  Several possibilities for earning Bitcoin are presented:


Mining
Performing sponsored actions
Using certain services that offer Bitcoin as an incentive
Performing mechanical turk tasks
Investing
Betting


The page at guadagnarebitcoins.altervista.org does not itself offer any service, and appears to simply offer information.  Therefore, the site itself is not a "scam."

However, as the site references a number of different third-party sites and services, you may find that your experience with those individual sites  will vary along a continuum of legitimacy (or lack thereof).

All of the proposed methods involve some non-zero amount of effort.

Considering the proposed methods ideally involves a good deal of judgment, self-knowledge, and reflection with questions like:


Will mining result in the profit I think it will?
Is this a good ROI for my time and money?
How much do I know about investing?
How much time and/or money can I afford to lose?
Is gambling a good way to earn money for me?
Do I have reasonable confidence that the service will pay me?


And so on.