Unless you have only a handful of people attending your conference, you'll need some sort of management system. In most cases, a simple merge database will suffice for mailings, conference lists, generation of name tags, etc. For larger conferences, consider a more capable database that also can handle many fields (e.g., presenter status, dietary requirements, etc.) For income and expenses, you may need a spreadsheet program. And unless you have a graphics department to prepare your program and brochures, plan on learning more about your favorite word processing program.