One of my biggest problems with Android tablets is that they’re not useful for much. The Motorola Xoom is the best industrial-strength tablet I’ve seen and the Samsung Galaxy Tab 10.1 is one of the most elegant mobile devices ever built, but neither of them will let you access your Gmail account without an Internet connection.

I didn’t realize how bad Android Honeycomb tablets were in terms of productivity until I used the now-defunct HP TouchPad, which runs circles around Android tablets and the Apple iPad in terms of its basic productivity features — accessing email and calendar offline, copying and pasting between mail messages, quickly flipping between Web pages and email, quickly flipping between IM and your calendar, etc. That’s why I praised the TouchPad as highly useful for business professionals.

Android tablets have a lot of untapped potential as business devices because of the flexibility of the platform. But, while devices like the ASUS Eee Pad Transformer have made strides in turning Android 3.0 into a more business-friendly platform, the best hope for professionals who want a corporate Android tablet could be Lenovo’s forthcoming 10-inch ThinkPad Tablet.

Lenovo has recognized that it’s going to take a mix of the right hardware and software improvements to make tablets useful for more business buyers.

On the hardware side, Lenovo has integrated a USB port for data transfer, a 3-in-1 card reader for media management, a Mini-HDMI for running a presentation, and a dock connector for using the tablet as a full PC at the office. The ThinkPad also offers accessories that can boost productivity like a padfolio cover that includes a keyboard and trackpad mouse and a digital pen for writing notes.

On the software side, the Lenovo tablet includes notetaking software for converting handwritten notes into digital text and drawings, Dataviz Documents to Go for working with Microsoft Office documents, Citrix Receiver for accessing corporate apps over the network, and Good Technology’s enterprise software for highly-secure access to email, calendar, contacts, and corporate collaboration systems (for those companies that have Good for Enterprise on the backend).

Like the iPad, the ThinkPad Tablet starts at $499 for the 16GB Wi-Fi version and scales up from there. Lenovo has started taking pre-orders, with an estimated ship date of August 30. The handy padfolio case will run you an extra $100, the digital pen is another $30, and the dock is $60. Still, since this has the potential to be more of a laptop replacement, I expect plenty of suits to show an interest in this one.

Take a look at the three Lenovo slides below that show the ThinkPad’s focus on corporate users, and then watch Lenovo’s two-minute promo video to get a look at the real thing in action.