Why can't I be Sherlock, Indiana and Marie Curie all at once?

You could join the military. But when people say something that "makes a difference", I think what they really mean is "big important well-known thing that cures cancer/acne/suffering". Because, frankly, being really good and humble and courteous at any job makes a difference. You can serve coffee in a way that makes people feel better. You can make change, sell tickets, answer phones--it's not the job, it's the way you do it.

Come join the not-so-dark side of international development. Charities, government agencies, churches, and foundations all over the world fund work to help developing countries. This work ranges from things like mapping rains in the Horn of Africa to predict famine (FEWS-NET, a USAID funded project) to researching drug-resistant tuberculosis treatment for people in the mountains of Peru (Partners in Health, out of Boston) to the Clinton Foundation funding internships for rural agriculture in India. Though you'll probably toil for a few years at a desk, there are some travel opportunities available at the lower levels (Peace Corps, for one, though some US-based non-profits and USAID contractors get you out to the field as well) and many of my 30- and 40-something colleagues travel extensively all over the world. The work isn't glamorous; it's often frustrating and mind-boggling and full of AUGH, but it really makes a difference. There are a million different ways to enter; nominally, I work in global public health, but though I work with doctors and nurses, I work with tons of public health people and monitoring people and lawyers and architects and lab technicians and accountants and project managers and pretty much anything. I did my degree in IR and sociocultural anthropology; no one cares, though. I have learned a ton in all of my i-dev jobs.

In many ways academia sounds great for you -- if you can pick an area of study that a) you have passion for, and b (optional): has some need for research involving travel. Academics are the most-traveled people I know, some because it's in their research (the Archaeologist who studies daily life in prehistoric Guatemala, the Geneticist who studies diseases in Africa), and others because of conferences and collaborations, and talks around the world -- it might take a while for them to work up to that (a first-year grad student probably won't get to go to the awesome conference in China or be invited to speak in Vienna), but the more senior faculty travel basically as much as they want (especially those in fields that are well-funded).

I'm going to agree that this is mostly in your head. I've seen tons of non-profit types burn out because they realize the problem is bigger than any NGO, while it's easy to realize why any given cog is important. I worked for a cosmetics company whose mission statement talked about how their brand empowered women through enhanced confidence. Being someone who hates morning rituals, especially make-up, I was pretty cynical about it. But many people aren't. I would say that what you want is the job you get after a year or two of learning the ropes. If you're lucky enough to get a boss that isn't into micro-managing. The actual subject matter is less important.

If you're a US citizen, I understand the foreign service is looking for smart people. I don't know much about the culture, but the work itself might fit your requirements.

Some of what you are attracted to makes me think you'd like to be a conservator or collections care manager in a museum. These are people who work with objects and keep them in good condition. There's a lot of travel, for two reasons: one, research and training, and two, courier-ing objects going on loan to other museums. It's arty and intellectual, and there is always a new project around the corner to help you avoid boredom. Conservation in particular invoves physical labor - things like lifting and moving and packing - but also fine-motor labor sometimes, depending on what kind of conservation you specialize in. It can be sort of adventurous in a new-discovery sort of way, though it tends to fall a little short of Indiana Jones there's a bit of that flavor. Here's the Federal with info on training and stuff, and here's a basic outline of a http://www.ehow.com/about_6678567_job-description-museum-collections-manager.html, and here's http://en.wikipedia.org/wiki/Art_conservation_training.

I work in international development and I do like my job. I have been a long term volunteer (similar to Peace Corps, which is what started me in this area), worked for aid contractors, worked for a university, in government, and non-profits. I have travelled to many countries in Asia, Africa and the Pacific as part of my job (this year will also go to the Middle East and Latin America). I have managed or worked on projects in a whole range of sectors in these countries - expanding university education in Africa, HIV program for Tibet, legal reform against trafficking in persons across Asia, corporate social responsibility partnerships, road engineering, elementary school education, government capacity building, anti-corruption, health system development, regulation reform, and special economic zones Having said that, there have been times when it has been boring and desk-based and with little in the way of challenges. I am now in a management position where I get a lot of intellectual stimulation and challenges, but it is also balanced with operations, which is a good mix for me. I manage a major relationship for my organisation, but also am responsible for a lot of people out in the field - so in the last month, I have had to coordinate responses to a cycle threat, an earthquake, a case of dengue fever. People often say 'oh it must be rewarding to help others'. I like that my job and my organisation reflect my values, and some of that is around helping others. But honestly, I would not undertake many of these projects on a purely domestic basis because there is so much challenge in working internationally and cross culturally. I have predominantly had a 'head office' career, but you might prefer a field-based career. Also, I am more generally skilled in strategy and program management, rather than having a technical specialty. If you have a sociology background, you might get interested in program evaluation and effectiveness. Check out the American Evaluation Association. It is challenging to demonstrate whether a program has made any difference, and also evaluation usually involves lots of field work.

While I think development work might be a good fit, I just wanted to suggest the Foreign Service (particularly as a consular officer) as another option. Basically, as a consular officer, you are looking at complex, high-stakes puzzles on the visa line, with only a very limited time to solve them. You can certainly enter a flow-like state. If you work on the American Citizen Services side, you are helping out fellow citizens who need your help abroad. Often, they really have no other place to turn, and you can make a meaningful difference for them. Best of luck in figuring out your path!

How about one of the UN agencies? Whatever you pick, please accept it might take a few years of less stimulating work before you get to the exciting stuff. Don't be discouraged, and be realistic. Good luck.