If your phone is jailbroken, there are a few apps for viewing .pdf files - PDFViewer being the longest established one. WildEyes will also let you view them via Safari. Don't know of a native app for .doc files though.
If you're not jailbroken, you can mail them to yourself as attachments and view (not edit) on the iPhone. Or try out the Glide Mobile site, which I think lets you view and edit Word docs ...