LucidChart is a free (with a premium option), web-based flowchart creation tool. It appears to be quite easy to use, yet very professional.
If you are looking for software to install on your PC, remember that OpenOffice (or Go-Oo) offer Draw, a versitile and powerful drawing program (that doesn’t have a counterpart in Microsoft Office, either) which can be used for flowcharts, as well.
found via LibrarianInBlack