Many businesses use Microsoft SharePoint to enable collaboration over Office files. Dean Beeler's $15 SharePlus Office Mobile Client lets iPads be part of that collaboration. You can test it out with the free SharePlus Lite version.

For just file exchange with SharePoint, Aircreek offers the $7 Filamente app. And consider getting the free Moprise if all you need to do is view SharePoint-provisioned documents, and cut and paste their text into your other iPad applications.

ERP and CRM access

The free SAP BusinessOne lets you view reports and content, process approval requests, and manage client and partner data in your SAP ERP system.

TE's $1 SAPplApp provides access to your SAP ERP system after you connect to your corporate VPN, so you can monitor your business transaction data.