Two Easy Ways to Create and Share Diagrams in Your Google Drive

1- Lucidchart

Lucid chart  allows you to create and insert diagrams, flowcharts and mind maps into your Docs. Some of the features it provides to users include: hundreds of shapes and templates to choose from, drag and drop to add your own images, export to (vector) PDF, PNG, and JPG, embed diagrams in blogs or wikis, import documents from Microsoft Visio (.vsd, .vsdx and .vdx) and many more.

2- Gliffy

Cliffy is another great tool to use in your Google Docs to create professional looking diagrams and flowcharts. Some of its features include: easy-to-use diagram editor, extensive shape library with hundreds of industry-standard shapes and connectors, snap-to-grid, drawing guides, shape alignment and distribution tools, great for drawing a basic diagram, flow chart, UI mockup, site map, network map, business process model, org chart, floor plan, venn diagram, SWOT analysis, and other technical diagrams.