Note: Whenever possible, we link to Web-based URLs, however some links require iTunes to view.

Making one of the strongest runs at enterprise users so far is Salesforce Mobile. Meant as a supplemental rather than a stand-alone tool for the iPhone, this application requires the user to have an Unlimited Edition Salesforce license or a Mobile License for use with an Enterprise or Professional Edition account. Since Salesforce Mobile stores data right on your phone, you can access your customer information without a wireless connection.

Additionally, any third-party apps created on the company's development platform, Force.com, can also be deployed on the iPhone. Before you rush out to download Salesforce Mobile, be aware that many users are complaining that the app lacks the ability to edit data, and they criticize installation issues which is surprising since this isn't Salesforce's first foray into mobile apps.

Another big contender in the App Store's business category is Oracle's business intelligence (BI) offering, Business Indicators [iTunes link]. Like Salesforce Mobile, it's free to download but requires an Oracle Business Intelligence Suite, Enterprise Edition Plus and Oracle Business Intelligence Applications, Fusion Edition to use. Once installed, it promises to deliver information on "pre-defined and customized" metrics, analytics and reports.

The Omni Group has created a mobile version of OmniFocus, the robust task-management system aimed at professionals. Available for $19.99, OmniFocus for iPhone synchronizes with its desktop counterpart via MobileMe and can also be used as a stand-alone version. OmniFocus lets you create tasks and lists, then uses the iPhone's location awareness tools to point out what tasks you can accomplish based on where you are. A few users are reporting problems with the OmniFocus app, with most issues apparently related to syncing.

Enterprise users who don't want to pony up money large amounts of money for a single application can assemble their own collection of work-related apps at little to no cost just by digging around a bit.

If you also support other smartphones, be sure to read our recommendations: Six Free BlackBerry Downloads You Don't Want to Miss and Seven Fantastic Free Windows Mobile Apps.