SummaWiki enables Wikipedia Page Preview functionality for the whole web! When you hover your mouse over a wikipedia link this extension will display an in-page popup that mimics what would be displayed if you had done that on a wikipedia page.
Download the code here (specifically the manifest.json and content.js files) and save them in a folder locally. In Chrome, go to the "Manage Extensions", make sure you are in "Devloper Mode", click "Load unpacked" and select the folder where you saved the files.
The extension should now be loaded and visible in your extensions list.