No experience with servers, however, some alternatives to consider below.
There are some wireless external hard drives that can be used with the iPad.
The Kingston Wi-Drive, which costs $50 for the 16 Gigabyte, and then $30 more for every 16 gigs more. It works by you turning it on and then accessing the files on it from an app that you download on your iDevice. You can access music, movies, and other stuff. No connections or anything, it works like a WiFi connection, you connect to it from the setting on the iPad under wireless networks.
Then there is the Seagate GoFlex, which some would recommend over the Wi-Drive. But this one costs $199 and had 500 Gigabytes of storage. It works the sameway as the Kingston: no wires, runs over its wireless connection. You can actually fit up to 300 HD movies on it.
Another option:
Expand your iPad's storage capacity with HyperDrive
http://www.macworld.com/article/1153935/hyperdrive.html
On the road with a camera, an iPad, and a Hyperdrive
http://www.macworld.com/article/1160231/ipadhyperdrive.html
Mac - How to Move the iPhone & iPad iTunes Backup folder to an External Hard Drive
http://osxdaily.com/2011/03/05/how-to-move-the-iphoneipad-itunes-backup-folder-t o-an-external-hard-drive/
Windows - Change iPad default backup location
http://apple-ipad-tablet-help.blogspot.com/2010/07/change-ipad-default-backup-lo cation.html
Windows - Changing IPhone and iPad backup location
http://goodstuff2share.wordpress.com/2011/05/22/changing-iphone-and-ipad-backup- location/
Cheers, Tom 😉