i think a better question is what areas are in application development. you have the project manager, business analyst/consultant, Tester, Application Programmers, Graphic Designers, Security Officers, and Database Engineers.
a few of these can be combined, but it is usually not a good idea for one person to do everything. the worst is seeing a programmer try to do graphic design. just the thought makes me shiver. Then you have the graphic designers that try to code. That can be equally as scarey.
I have yet to personally see a person that kicks butt in all 4 main layers of a project. (Requirements, UI, Functional, and Database).