How to actually read ebooks

As more and more books appear in electronic form, I'm looking for a way to actually read them. Just staring at the PDFs on screen isn't enough. I want to:

• Highlight important parts and put notes and bookmarks there.
• Have some kind of synchronization mechanism, since I use one computer at work and a couple of others at home and of course I want to see my annotations in both places.
• All this should preferably be cross-platform (Windows and Linux at least).

Is there anything – possibly an on-line service – that would fulfill these needs? Foxit reader has good annotation capabilities, but only on Windows, and no way to sync anything. Perhaps the sync thing could be accomplished by (mis)using some version control service like GitHub, but it feels a bit clumsy. Or then of course I could store all my books in an USB stick, but…

Any ideas/experiences?

Edit: I found that Foxit Reader 3.0 works quite well under Wine in Ubuntu. Add Dropbox to that, and there it is… Everything I asked for 🙂

Foxit Reader 3.1 seems crash with Wine, but 3.0 works flawlessly so far.