I just posted this in another discussion. If you have GoodReader installed, email the document to yourself, open in GoodReader and upload to DropBox.
You can also do this with the DropBox app itself.
@OP:
SMEStorage is a cloud service aggregator. It allows you to combine several cloud file services in one place. You're not duplicating the files, just adding another layer of organization to access them all in one place.
SMEStorage's free account allows you to add two accounts. DropBox is one of the supported accounts types. This is important because SMEStorage also has a WebDAV service they call Cloud. Using the WebDAV features in Pages you can upload/download files to DropBox through SMEStorage.
While it is possible to create an SMEStorage account and add Cloud to it for free, I recommend purchasing the $4.99 iSMEStorage app. One, it sets it all up for your. Two, it allows you to manage your account on the iPad. This is useful, as I'll point out in the caveats to follow.
It is not a perfect solution. The file structure is much more complicated, even the simplified view, so you'll spend more time navigating to your DropBox folder. Also, files added to DropBox directly (not using the iSMEStorage app or website) are not automatically updated on the SMEStorage site. You'll need to open the iSMEStorage app (or visit the website) and refresh folders before opening Pages, to be sure that you see the most up to date file lists.
The marjory of the time I find it simpler to use a free Box.com account for cloud storage and sharing my iWorks files. It does not have the nice sync app on the computer side (you have to use their web site), but they have WebDAV, and it works smoothly with the iWorks apps. The Box app on the iPad is similar in function to the DropBox app; and Box is almost as well supported by the top document apps as DropBox.