Ask YC: how do you manage bookmarks?

I'm getting a little frustrated with existing bookmark managers. I want the ability to sort/search by tag and to have bookmarks synced across multiple machines. Delicious is the best I've tried but I don't like how bookmarks are public by default. It's understandable for a social bookmark service but I'm looking for something that keeps bookmarks private - I don't care about sharing them.

FF3: the built in bookmark manager is awful. Tagging is a great feature but badly implemented. The default right-clicked 'properties' dialogue for bookmarks doesn't allow me to add or edit tags. I can't easily search or list bookmarks by tag and there's no way to list untagged bookmarks. It feels like the developers added tags as an afterthought.

Foxmarks: great service but has similar limitations to FF's own bookmark manager.

What other solutions are people using?