Gladinet Cloud (http://gladinet.com/ ) works superbly with DreamObjects. For Windows - integrates with Windows Explorer as a mapped drive. Also has backup module.
More info on the plans and costs (free version vs. $50 version for lifetime license) at http://gladinet.com/plans.html, good info at http://en.wikipedia.org/wiki/Gladinet
I've used it for three years, very flexible. Works with multiple (more than a dozen!) providers like rackspace, Amazon S3, any Amazon S3 compatible service (such as DreamObjects), Box.net, Google drive (formerly Google Docs), Microsoft Live Skydrive, Peer1, any WebDav (anonymous or generic), any FTP (anonymous or logged in) and others. One big advantage I found when comparing with other packages three years ago when I researched and bought it is the desktop interface, with ability to map to a drive and Windows treats it like any other mapped drive in Windows Explorer. Can mount and unmount drives at will (useful for security if someone else will use your computer.) Can encrypt, can backup. Well written and well supported by email and by support wiki, no phone support available but largely self explanatory. Another advantage: no monthly or annual fee. Supposedly (per web site, I did not verify) was awarded PC Magazine's The Best Free Software of 2012 award for Backup/Sync/Storage.
Other competitors for S3 access that I recently researched but haven't tried the product (I was searching for WebDav access but didn't realize Gladinet Cloud already has it!) are as follows. I have not tried them but read their websites for comparisons and features I needed and they look promising for various reasons:
SouthRiverTech for S3, http://www.southrivertech.com/
http://www.southrivertech.com/download/index.html for trial
To buy $70/year, $95/two years: http://sites.fastspring.com/south/product/webdrive?action=adds
Looks like high quality, professional, well marketed product (expensive!) Did not check to see if it can be adapted to DreamObjects, or source code adapted to do so.
CarotDAV - http://rei.to/carotdav_en.html
For windows only. Free of charge, compliant with multiple standards, source code available. Works with SkyDrive, Dropbox, GoogleDrive, Box and SugarSync. No mapping of drives - seems to act like an FTP client (also runs with FTPS, see main webpage for all features and standards.) Per web page, "CarotDAV is a Simple WebDAV / FTP / SkyDrive / DropBox / GoogleDrive / Box / SugarSync client for Windows OS, available free of charge. It is also able to read GoogleDocs or IMAP."
tntDrive - http://tntdrive.com/
For mapping S3 buckets as network drives.
$40 for pro, free 30-day trial
http://tntdrive.com/buypro.php to download or purchase
S3 Browser - http://s3browser.com/ by the same company is free, and can map a bucket as a drive, seems to act like a Windows Explorer for the S3 drive. Not sure if either the tntDrive or the S3 Browser can be adapted to DreamObjects, or source code adapted to do so, did not check into that.