The Gliffy plugin allows you to create diagrams and insert them into your posts or pages. Draw all kinds of diagrams: flowcharts, UI mockups, UML, etc
Make sure to configure your plugin before use.
Create a new diagram by going to the object menu and selecting add new. Provide a name for your diagram.
The Gliffy Editor will launch in the window. Make sure to click on "share" to set the visibility of the document to "make public". When you're done editing it, press the link "Back to WordPress"
Add your new diagram into your post by clicking on the media button and then selecting your desired diagram.
The post will now contain a "macro" that tells WordPress that this is where your diagram should go.
And here is what the diagram looks like in your post. You can click on it to see a larger version!
Diagrams listed in gallery view for editing