What kind of jobs are there in the marines?

At the link you will find a list of jobs available in the Marine Corps. You initially enlist for 8 years (usually 4 active duty and 4 reserve (active or inactive)). You theoretically can serve as much as 30 years, provided you achieve the appropriate rank to do so. When you enlist, you will serve your first term in whatever job you enlisted into. When you reenlist, you may be able to change jobs. https://en.wikipedia.org/wiki/List_of_United_States_Marine_Corps_MOS

The other guys have it pretty well covered. If you're considering going into something more like programming, electrical engineering, nuclear engineering etc.. You might consider the Navy or Air Force. They serve less of a combat role and more of a technical support role in the military.

Use the link Provost posted. The USMC has pretty basic career fields mostly combat related I guess you would say. Infantry, Armor, Artillery, Logistics, MP, Intel, Avionics, Comms and Maintenance and pretty much their main focus. Everything else comes from the Navy as they're a department of the Navy. Also when you enlist you're obligated to serve 8 years. Not all that time has to be active duty. Most serve 4-6 years active duty, then 2 years reserve. Either way you serve 8 years. Remember that. At the end of your service time you can choose to cross train into another field if you meet the requirements.