It's been a year since the Google Chromecast was first introduced, and Google is celebrating with a new deal for Chromecast buyers that almost rivals its debut offer of three months of Netflix free.

If you've been interested in the Chromecast but still haven't decided to buy the $35 video and audio "casting" HDMI dongle, Google has an offer for you as part of its celebration of the device's one-year anniversary: buy a Chromecast anytime starting now going through the end of September, and Google will compliment your new purchase with three months of Google Play Music All Access. It's a great deal for anyone who has needed a little extra incentive to get a Chromecast and who has been looking to try an unlimited music streaming service.

Google Play Music All Access -- which, of course, is streamable to your HD TV on the Chromecast -- normally costs $9.99 per month, so the deal is basically offering $30 worth of music for a $35 purchase. Google Play Music All Access offers about 25 million songs without ads, making it far better than some competitors, like the recently launched content-anemic Amazon Prime Music service, so it's no small thing that Chromecast buyers can get it for free for three months. That said, the web giant's music service is not as popular as Netflix, which partnered with Google last year for the Chromecast's debut to offer a similar three months of service free -- which quickly resulted in the Chromecast being sold out after about a day.

If you already have a Chromecast, you're not being left out (as long as you don't already subscribe to Google Play Music All Access). Just go to Chromecast's "Offers" page to authenticate your device and get your 90-day Google music subscription.

But be forewarned! This is one of those must-cancel offers: After the last day of your complimentary subscription is over, Google will start charging you the $9.99 per month otherwise. Set yourself a reminder if you don't ever plan on paying Google for streaming music.

Google also announced some (select) statistics about the Chromecast's success after one year. For one, Google says its fleet of Chromecasts have carried out more than 400 million "casts" -- or individual streams of content from mobile devices or computers onto the television through the Chromecast. Additionally, Google announced that the device is now available in 30,000 stores across 20 different countries. Google didn't (and hasn't yet) tell any specific sales figures, but it's still on Amazon's best-seller list one year later -- after it almost immediately jumped into that category after launch -- and sources like CNET are figuring it's safe to say that "millions of Chromecasts" have been sold by now.

If you're not familiar with the Chromecast, it's an "HDMI dongle" -- not much bigger than a flash thumbstick drive -- that plugs directly into your HDTV's HDMI port, with a USB cord for power. Connecting to your WiFi, and soon directly without WiFi, the device communicates with Android and iOS devices to allow tons of popular apps -- get the full list here -- to stream music, movies, videos, and photos directly onto the largest screen in your house. You can also stream web content from computers using Google's Chrome browser.

Besides apps, recently Google announced it had added a screen mirroring feature for Android devices -- just like Apple's AirPlay -- that allowed still-unsupported apps to stream to the Chromecast, too. Right now only Google Nexus devices, Samsung flagships starting with the Galaxy S4 and more recent, and the most recent LG flagship smartphones can use the Chromecast's screen mirroring feature, and that's only if they're running Android KitKat or higher. But the list of supported Android devices is expected to expand, just as the number of "castable" apps continues to grow.