For instance, there's no shortage of apps for business travelers. In what's likely the first in a series, Frommer's has released its Guides to San Francisco and New York [iTunes links], that provide maps and up-to-the-minute information on the 'cities' dining, hotels, nightlife and attractions. There are also plenty of apps in the Navigation category [iTunes link] that provide maps and public transportation schedules for several major metropolitan cities including New York City, Washington, D.C., and Berlin, Germany.

Once you get where you're going, use the free app from Hotels.com to decide where to stay for the night. As you travel, use Expense2GO to keep an ongoing expense report, which, incidentally, synchronizes with Salesforce CRM. Overseas travelers will appreciate the App Store's Education category [iTunes link], which is packed with phrasebooks, translation dictionaries and study guides in several languages.

There are also plenty of business-oriented apps for people who never leave the home office. ZeptoPad is a handy mind mapping tool. Use it to take notes and record impromptu brainstorming sessions, then e-mail it to yourself or others as a reminder of the conversation. Or simply record the entire session using QuickVoice, a voice recorder with a slick interface and several useful features, including pause record, pause play and finger scrolling through files.

If it's a to-do list you need, you can't do better than Todo by Appigo. Though it's not free, like many of the other to-do list apps, this one integrates so well into the iPhone, you'll never know it didn't fall from the Apple tree. Use Todo alone, or sync it with one of the popular Web-based to-do list solutions like Remember The Milk or Toodledo. For a no-frills—and free—checklist, try the similarly named To-Do.

All the software at the App Store can be downloaded to a corporate iPhone via iTunes. Instructions for deploying iTunes and installing applications are in Apple's Enterprise Deployment Guide [PDF].

Although the number of consumer-oriented solutions in the App Store clearly outweigh what's available for business users, as the iPhone becomes more widely adopted in the enterprise, the number of useful apps for the professional is likely to grow exponentially.