Google has been working on a new rich notifications feature for Chrome. The goal is to both revamp Chrome notifications and also make a new home for Google Now cards.
The feature is still in the works and is not even enabled by default, but if you're running a dev channel build of Chrome you can now play with it.
Google created a Chrome app to test the new notifications, all the app does is send the browser different types of notifications.
First, you have to enable rich notifications in chrome://flags, the feature is only available on Windows and Chrome OS for now. You also need to have the "Experimental Extension APIs" flag turned on.
Then, you can install the test app, dubbed Notifications Galore, as long as you can grab it. You can find it here, but the link may die.
Unzip the archive, go to chrome://extensions, enable "Developer Mode" and then click Load Unpacked Extension. Select the folder where you extracted the app and it will be installed.
You'll find the app in the new tab page, launch it and you'll be able to test the different types of notifications.