What about using Firefox's bookmarks sinced by Weave? Its private, its safe, it supports tags, it is easy acces the bookmarks through the awesome bar, etc.
I'm using Weave (just for bookmarks), and couldn't be happier. On any given day I might use a Windows PC at work, my Macbook Pro at work or at home, my wife's Windows laptop at home, or my main desktop at home which dual boots Vista and Leopard. Weave just works, and I have all my bookmarks synced on all of these computers.
