In the age of instant messaging, the longest thing you may read in a day is the text of the "Terms of Service" for some new software or web service. Oh, wait, I forgot: no one actually reads those.
It's a frightening thought that even lawyers don't read boilerplate contracts. The general consensus seems to be: even if I did read the terms of service for any given site or application, I would still sign up anyway. So, what's the point?
Websites generally make revenue from advertising. By referencing the content in your personal information, they can maximize the value of ads. Every piece of data that a company gathers from you is likely used as a data point.
Facebook, for example, makes this pretty clear in their terms of service: "you grant us a non-exclusive, transferable, sub-licensable, royalty-free, worldwide license to use any IP content that you post on or in connection with Facebook (IP License)."
Your privacy rights are even further compromised by your smartphone apps, which may be spying on you without your knowledge.
More Than Privacy Rights
Consider LinkedIn. If any group of on the web would be inclined to read the terms of service, it would probably be the people on LinkedIn. And yet, LinkedIn has some of the worst terms of service out there.
In a confused block of text, the company states that it has your permission to basically do anything it wants with your information. In other words, the company can claim anything you share on their service and share that information for its own profit.
How to Quickly Know What You're Getting Into
It's important to understand what info a company can access and how they can use it. Knowing how LinkedIn uses your information, for example, might change what you decide to post on your profile. If you have a great idea for a new business, it may be in your best interest to keep it off LinkedIn.
There are resources on the web that make it easy to know if company's terms of service are completely evil. For instance, check out Terms of Service; Didn't Read, a browser ad-on that rates and quickly explains websites' terms of service.