Another one of the great things about Android (if you're a geek or a tinkerer) is that you have lower-level access to the system itself. Astro is an app that lets you navigate the Android file system, which is mostly just interesting, but can be handy once in a while.
12. Speed Test
I'm obsessed with running speed tests to check my bandwidth in various places, both to see 3G/4G fluctuations and to check the quality of Wi-Fi. There are a number of really good speed test apps, but my favorite is the Speedtest.net app. It's generally consistent and it has some of the best graphics and options.
13. Amazon Kindle
I've never completely warmed up to the Amazon Kindle e-reader, but I'm a big fan of the Kindle mobile app. Since it was released I've read a lot more books simply because my smartphone is always with me and I can pull it out and read a few pages anytime I've got a couple minutes free.
I've written a lot about Google+ since it launched in July and I'm pretty active over there (+Jason Hiner). One of the great things that Google did was to release a Google+ Android app at the same time it launched the service as a beta. And, surprisingly, the app was actually pretty good and has been improved since. It immediately became one of my most used mobile apps and definitely stole some of my time away from Android's Twitter app, mostly because Google+ is a little more interactive.
15. TED Air
The TED conference features a meeting of the minds of some of society's most influential thinkers. You'll disagree with some of them since there's a large diversity of viewpoints, but many talks are worth listening to in order to catch the latest creative thinking on society's biggest challenges. The cool thing is that they've taken the videos from the conference and made them freely available on the Web. The TED Air app provides a great way to access the videos on a mobile device. I hope more conferences follow TED's lead on this.
16. Google Goggles
This is a fun app that is a little bit ahead of its time. It does visual searches. You can take pictures of things and then the app tries to tell you what they are. It's limited in its scope but it is pretty cool, and it's definitely a peek into the future. One of the coolest features is the ability to take pictures of text in a foreign language and let the app translate it for you. In a foreign country, this can help you read street signs and avoid going into the wrong bathroom. :-) On a more practical level, Goggles is a QR code reader.
Photoshop is, of course, the best known photo editor in the world and its mobile app doesn't do anything to hurt that reputation. But while the desktop version is known for having a zillion features, the mobile app is distinguished by its simplicity. It's the best Android (and iPhone) photo editing app for simple crops, brightness adjustments, and sharpens, for example.
As much as I like the Kindle ebooks, I actually consume more books as audiobooks via Audible. With the Audible app you can connect to your Audible library and download over the air. The app also gives you a self-contained player optimized for audiobooks, with a skip-back-30-seconds button and the opportunity to make notes and bookmarks (although I wish the app would store these online so that they could be accessed from the Audible site).
If you want to impress your friends with a mobile app, show them Shazam. Ever hear a song being played at a store or on the radio and ask yourself, "Oh, what song is that?" That's where Shazam comes in. Just hit the button and let it listen for 15 seconds, query its database, and then return the name of artist and the song. It has about an 80% success rate. This one isn't particularly productive, but it is really cool. (You have to live a little, every once in a while.)
20. Google Finance
This is a great little app that regularly gets overlooked. It connects to your Google Finance account, where you can set up a list of stocks and companies to follow and sort them into groups (portfolios). The app provides three simple tabs -- a look at the market, a look at your portfolios, and the latest market news. It even does real-time updates when you have the app open.
What are your picks for the most useful, valuable, and productive Android smartphone apps? Post them in the discussion below.
Jason Hiner is the Global Editor in Chief of TechRepublic and Global Long Form Editor of ZDNet. He is an award-winning journalist who writes about the people, products, and ideas that are revolutionizing the ways we live and work in the 21st century.