Sitecore has provided many great ways to plug into their architecture via pipelines and configuration patches. I'm confused however how to present a simple dialog to the content editor whenever they click a button in the CE. Is there an easy way to do this without a code deployment? I guess module packages would be ok, just no downtime to the users.
You can install Sitecore Powershell Extensions.
This module allows you to create dialogs using Powershell Scripts and create buttons which you can connect to various places in Content Editor (context menu, ribbon, etc.)
This screenshot if from one of the examples. The code underneath the dialog is used to create it.