Adding files to apps

[Crispy]

I have 3 ebook readers and 2-3 video players. To add files to them, I have to add them to the specific section in iTunes. But I found no way to share these files. e.g. I added some ebooks to iBooks, then to add them to Stanza I had to again copy them to the device. Added some videos in player A, and had to again copy them for player B.

Is it really the only way? I can't believe its this unfriendly, and I don't have enough space to keep multiple copies of the same media. And iTunes won't even let me copy them from one app to the other, I have to find the files on my pc first!