Gliffy

I really like the ease of use of this product and the short learning curve when I first started to use it initially. They continually enhance this product to adapt to my needs and I actually have fun doing the designs I need to for workflows to brainstorming.

Gliffy is easier to learn than Visio, fairly intuitive and the common functions you need are close to hand (on right click or contextual menu button close to selected item).

Was quicker to draw a medium complexity diagram with boxes and connectors than Visio (or Powerpoint), and the resulting diagram looked good. Good range of available symbols and easy to add your own stencils from a SVG-based artwork (and JPG importing was easy too).
Small native file format, and it is text based (JSON) so it is searchable (and hackable if needed).
But there are limitations, which means it for the most complex or structured diagrams it can't replace Visio, OmniGraffle, or a Architecture tool (and would not replace Autocad or similar either)

I can see this may work better on tablets/touch screens than Visio

No bulleted text/numbered lists
Connectors won't "hoop" over lines, and you can't add additional bends in connectors (there are workarounds--import "hoop" shape or use a UML shape to fake a hoop with multiple lines)
Can't have text less than 9px in size.
Limited import and export options.

But the product is continuously developing.

Gliffy has been a great addition to our organization as it is being used by several department and practice groups to diagram processes, as well as organization charts, and technical documentation. It is easy to administer, and simple to learn with

Helps me create flowcharts to visualize complex processes and relationships