Gliffy Offers a free online subscription. Create flow charts, floor plans, technical drawings, etc.
Lucidchart Offers a free online subscription. Integrates with Google Drive and Google Apps.
Mind Map Software
Creately Online diagramming software. Individual or collaborate.
FreeMind Requires download. Free open source software. Not as intiutive as Xmind
mindmeister Create a virtual mind map. Create way to organize thoughts. Ability to share and collaborate with others.
Xmind Requires download. Unlimited creation of maps. Sharing capibilities with paid version.