Are there apps or appliances available for iPad (or iPhone I suppose) that would allow me to backup the content (photos etc) of my iPad without a PC?
I was thinking of something like Carbonite/JungleDisk or the Apple Time Capsule.
You currently need to go either through iCloud or iTunes (PC/Mac) as per this kb article.
There are no other solutions that would allow you to do backups of the iPad.
I would strongly recommend you leave a feature request on the feedback page of the iPad and on the Time Capsule page. Apple read them and when they get enough request for a feature they get more incentive to implement it.