With your shiny new degree, you are now officially capable of bringing your calm analytical thoughts and youthful exuberance to saving the world. Whether it's fundraising for a children's charity, building houses in Guatamala, or swabbing the deck on the Sea Shepherd, many graduates want to help make the world a better place. Nothing wrong with that! Perhaps in university you volunteered for a charity. That'll help, right? And you can look at all of the wage slave graduates and feel smug that you are Helping The World.
True story: I have a friend who runs a charity shop. She has always aspired to work in the charity sector, and about a year after graduating she got the dream job. She is paid a reasonable salary, and works for a charity that helps disadvantaged children, using the money she raises in her shop. She assures me that she is glad of this, and does occasionally get a little weepy after a few pints if she's been out visiting one of the projects she helps. So the warm fuzzies do, in fact, exist for graduates.
Saving the world is still work. My friend is the only paid member of staff in her shop, and regularly works twelve hour days. She has volunteer staff who are erratic at best, and she has to deal with all of the HR, all of the paperwork, and most of the retail side of thing. And the health and safety. Don't forget that, it's important. She is currently dealing with a flasher who enjoys coming into the shop and revealing himself to female staff members. (They can't identify him, mostly because they don't focus on his face when he, ah, reveals his identity.) Basically, she has a job that is three times more difficult than most other people and she is emotionally tied to it on the basis that it does, at least, give her a small amount of the fuzzies. The fuzzies, it turns out, are not all that glamorous.
In conclusion: yes, you can get a job that will help you Save The World when you are a graduate. The myth is that it is in some way different from being a job. Nope, sorry, still got all the same problems and indeed a slightly higher percentage of the problems. On the bright side, you do at least get a slightly brighter sense of job satisfaction.
(Don't get me started on 'charity' internships. That's a post for another day.)