Since the launch of Apple's App Store, a steady stream of business-oriented applications have become available for iPhone users.

Most of the developers are independent, third-party start-ups, but big-name software vendors have also started clamouring for a piece of the action. Companies such as Oracle, SAP and Sybase have released iPhone applications that allow users to tap some of the functionality afforded by the traditional desktop versions.

Most of the applications can be found on the App Store, Apple's online market, where iPhone users can browse and download applications built for their devices.

Here are five enterprise apps that the big software houses are hoping will catch the attention of the growing iPhone user base, although none has yet to make it to the top downloads list on App Store.

Oracle Business Indicators
Oracle released its native iPhone application in July this year, becoming one of the first companies to release an enterprise application when the App Store opened its doors.

The business-intelligence (BI) tool is available as a free download, but customers must have licensed copies of Oracle's BI software running on their company's servers, because the mobile app draws reports and analytics from the on-premises software.

According to reports, Oracle last month said that the software had clocked 23,055 downloads since it became available.

Sybase iAnywhere Mobile Office
The database giant's iAnywhere software connects users to company email servers, based on Lotus Domino and Microsoft Exchange platforms.

According to Sybase's website, the software can help secure a company's messaging platform by providing access to email and contacts "without requiring changes to an enterprise's [main] messaging infrastructure".

Offline email access is also supported. The company also said it plans to upgrade the app based on version 2 of the iPhone software-development kit (SDK).

SAP
The business-management software maker released its iPhone version of a salesforce automation suite ahead of other platforms, such as the BlackBerry.

SAP said in a statement that the software will load business contacts, information on sales prospects and account data onto the device.

Salesforce.com Mobile
One of the earliest vendors to release an iPhone app, Salesforce.com in March showed off a preliminary version of its CRM product based on the beta version of the iPhone SDK.

The software connects users to their CRM records. The free version allows users to search and view contacts and accounts, but users need to sign up for the paid version in order to edit their data, according to Salesforce.com's website.

Web-based apps: NetSuite, SugarCRM, Zoho
These apps are not native iPhone apps but are meant to be launched via the phone's web browser. Some of the big names offering non-native apps include CRM vendors NetSuite and SugarCRM, which have released web-based ERP versions of their product offerings.

The apps are available in both hosted and on-premises versions.

Online office suite Zoho has also launched a mobile version of its productivity suite for the iPhone. This includes word-editor, spreadsheet and email programs. Users can view existing documents but not edit them or create new ones.