1. Evernote -
Availability: Android, BlackBerry, iPhone, Palm webOS and Windows Mobile
2. Bump
Availability: Android and iPhone
3. Apple's iWork Suite
When you're on the go, the work still needs to get done. Having the iWork Suite on your iPad will help you to be productive while you're away. Apple has taken some care in ensuring the word processing, charts and graphs and presentation software are each intuitive and easy-to-use on the iPad.
Availability: iPad
4. Dropbox
When you need to share a large file or simply back up some data, dropbox is easy-to-use and quick to setup. The first 2GB are free, however there is an option to pay for additional storage. Whether for business or personal use, we use dropbox all the time!
Availability: iPhone, Android, BlackBerry, Kindle Fire, iPad
5. TweetDeck
The beauty of Twitter is sharing on the fly. When you're away from your computer, take TweetDeck with you to keep in touch with your followers. If you're tweeting on behalf of a corporate account, it's all the more important that you're able to respond to tweets in a timely manner. TweetDeck will help you do just that.
Availability: Android, iPhone, iPad, BlackBerry
6. PrintCentral
If you are a frequent user of an iPad, the time will come when you want (need) to print something. PrintCentral will allow you to print almost anything! It's a paid app that comes with some additional features. But, for just under $15, the ability to print is well worth the price.
Availability: iPad
7. Square
If you're a small business that needs to begin accepting credit cards, Square is a great option. The app and the card reader are free. Instead you are charged a percent of each transaction. Square offers a great first step for those that are new to accepting credit cards.
Availability: iPhone and Android
8. Tripit
Keep track of business travel with ease. Tripit will store flights, car rentals and hotel reservations to make business travel a breeze. The basic app is free, or if you want to track frequent flier miles, you can upgrade.
Availability: iPhone, iPad, Android, BlackBerry
9. Facebook
Love it or hate it Facebook is a part of business. Facebook for mobile is easy to use and will help you stay connected wherever you are. The same rule of timely responses applies on Facebook as we mentioned on Twitter. If someone comments on your brand's timeline, giving no response or a response 3-days later is a social networking pitfall you'll want to avoid.
Availability: Android, iPhone/iPad, BlackBerry, Windows Mobile, Kindle
10. The Walking Dead: The Game
Look, we all know you're an overachiever that's working hard well after 5 PM. Take a timeout and slay some zombies. Call it multitasking; a bit of work and a bit of play. We won't tell anyone.
Availability: Android, iPhone/iPad
--
Checkout some other resources for the "best of" business apps.
Top 10 Must-Have iPhone Business Apps by PC World
The Best Mobile Apps for Business by Entrepreneur
20 Best iPad Apps for Business by Business Insider
5 Best Apps for Business by CNN Money