iSMEStorage (http://www.smestorage.com) now supports over 30 storage clouds and, using its CloudDav feature, can enable direct editing of documents in iOS app such as iWork.
Users can upload files directly to the iPad and iPhone via a web interface as well as from standard FTP clients over Wi-Fi. Popular clouds such as DropBox, Amazon S3, Google Docs, SkyDrive etc are able to be directly accessed using the WebDav protocol in editing applications.
CloudDev works with the iPhone, iPod touch, and iPad and requires iOS 4.1 or later. It’s available in the Apple App Store for US$4.99.