I've just published my first extension for Chromium browsers, BAT Ticker, to the Chrome Web Store.
It shows the current USD price of the cryptocurrency BAT along with the 24h change (direction is shown on the icon by the red/green badge colour, or click the icon to get the percentage value).
You can get the extension here on the Chrome Web Store, or I also have a project page here with more details and a link to the source code.