If you're willing to spend a little you can go to Vault.com and they have lots of info there. They have "employee surveys" which are basically these survey filled out by people in different industries where they describe the specific culture of the company they work for, they'll describe their compensation structure, and so forth. Really interesting stuff. Some people give a day-in-the-life sort of rundown. Tons of these surveys which are very helpful in figuring out what industries are all about.
There is also a site called Wetfeet that is similar, but like a smaller-scale version of Vault.
Also, contacting people as you suggested is a really great way to learn about industries and jobs. I've done a lot of that and people get very excited when they hear you want to talk to them because it makes them feel important and hey, who doesn't like talking about themself.