Given that the iPad doesn't run a standard operating system like Mac OS X or Windows 7, you may feel like you can't be very productive with a device that only runs an iPhone OS. Well, given that the iPad has a robust web browser, you can be productive if you leverage cloud computing resources. To start, we can use Google Docs (docs.google.com) and create/view/edit documents created by Microsoft Office (such as MS Word, Excel, and PowerPoint). Google Docs accepts most popular file formats, including DOC, XLS, ODT, ODS, RTF, CSV, PPT, etc.
So, who needs third-party apps for the iPad? You don't need to purchase iWork to stay productive. Just get online and rely on the cloud for your apps and documents.