I've finally got music and photos synching with GTKpod and libiphone. Music is fine, easier than ituNes. Getting pictures on the ipoD is slightly clumsy, but easier than making the iTunes on my wife's computer play nice with two separate accounts and finding a time when she isn't using it. (Itunes does not understand user accounts on Windows--even though my ipod is set up under a different user account, I have to hold shift when launching to be able to select my ipod files, and remember to switch it back before my wife uses hers)
The other major issue is ebooks. I use Stanza to read ebooks, and I now prefer reading on the iPod to reading a paper book. My page is kept, I have one thing to keep track of, and it fits a huge library of books in my pocket. Unfortunately the part of Stanza that loads your books isn't available on Linux, again requiring my wife's computer.
The final piece for ebooks on Linux was Calibre. Stanza on the ipOd has the capability to download directly from the web. Calibre takes advantage of this and sets your computer to serve your books. Another advantage to this is that the books are pulled onto the ipod, rather than pushed to it from the computer. This means that one install of Calibre could serve many people without bothering the user of the computer.
Calibre also converts to and from various document and ebook formats, so you can take a .pdf or .html file and turn it into a format your reader can use, although with some limits. One of the limits is dealing with an original that is badly formatted. Several of the books I downloaded had word wrap set so that on the ipod, I'd get a full line, half a line, then a blank line. The original document had lines that were set to a fixed length longer than the ipod screen can display. I fixed this by opening in Open Office, replacing all instances of two carriage returns in a row and replacing them with a ::::, then finding all remaining carriage returns and replacing them with two spaces. Finally, replace all the :::: with a carriage return, and you now have sensible paragraphs that will wrap properly regardless of screen size. Open Office can save in .rtf and HTML formats that Calibre can read.
Unfortunately there is apparently a bug in Calibre's .rtf conversion that makes pages after the first one blank.. Oddly, this is one page, regardless of font size--Decreasing the font to something barely readable showed more text, but still a blank second page. Saving as .html and using that to create the ebook solved that.
A lot of work, but in the end worth the effort. I now have plenty of reading material on my iPod, including quite a few Heinlein stories I haven't read in decades, and some I can't remember reading ever.