Almost always, nothing, no one cares, no one is going to do anything. As for e-mail, they want it most likely to sell it to companies that will send you spam, not dangerous, just annoying.
HOWEVER, in some extremely rare cases, if someone was extremely hell-bent on doing something bad, they could, but it wouldn't be easy. For the rest of this post, I will refer to someone like this, whatever their motives may be, as Black, to make it easier to follow.

Pictures- Pictures can be used for a variety of different data-gathering purposes for Black. Aside from behavioral information, pictures can be used to gather information on where you have been, where you live, were you eat, who your friends are, etc. Depending on the amount of pictures and the frequency of posting them, it may even be possible to create a timeline on how you spend your day.

Email- When you sign up for an email, you are asked for various information. I for one never give out any real information to email companies. Anyone with the know-how can hack your account and find out all of your information very easily, they just need to know your email address. This is bad, but linking this to other knowledge of you, could potential be much more dangerous.

Your Name- Your name seems like something that is no big deal, but in reality, your name is your first defense. With only a name, people with the know-how can track you down, find your billing information, find out where you live, what you spend money on, where you vacation with. After some serious research and assuming other things aren't safegaurded properly, they can find bank codes ss numbers, etc. So that everyone who reads this doesn't freak out, let me explain how this is possible (and how unlikely it is). Once Black has your name, they can find out where you live, this is very easy. One way is as simple as a phonebook, but there are plenty of others. Next, Black could for example go to your house, sift through your trash, mail, even break in and go through personal documents and computers while you are gone. This action could lead them to find all sorts of information. To give you an idea of how easy it is to find someone, I was once contacted by a friend who got stood up by someone on ebay, sold him fake golf clubs or something. He contacted me knowing I had a degree in Criminal Justice and experience tracking people like this. He did not even know the name of the person, and for whatever reasons did not have info on what account the money went to. All he had was the email. I traced it, followed it back to a company, in which I searched the database for his name correlating with the email address, then used his name to find his home address. All this was done 100% LEGALLY! and took a matter of 5-10 minutes.

Why this information is important- Obviously SS numbers and bank documents are not good to have floating around, but you may ask, so they know where I go to eat and where, where I hang out, etc. Who cares? One reason (among a few, but not many) is that some professionals use this information to time robberies, kidnappings, etc. For example, if you post pictures every saturday morning of you at a resturaunt with friends titled "friday night" Black will know you are gone every friday night, and can break into your house then. Also, some creep who sees a picture of your daughter on the internet and decides he wants her, can use information like this to track her and decided when best to make his move, or even be more suddle than that and find a way into her life, get her to trust him somehow.

These dangers are real but infrequent. I wouldn't worry about it too much, but be smart, shred important mail, don't keep the EXACT same schedule every week, and certainly don't advertise it.