Diagram Software [duplicate]
Two that I know of:
- Shapes - Cheap ($5) with a decent array of tools
- OmniGraffle - Expensive, but it can do pretty much anything, including reading Vizio files (Pro version)
It isn't cheap, but OmniGraffle from OmniGroup is truly outstanding. Student pricing is available, and substantially less expensive than full retail price. ($60 vs $100)