Sadly, everything I've tried so far has been painful to manage between two computers, (even between different browsers on the same computer).
So, right now I have different aggregations of bookmarks passwords in xmarks, delicious, google bookmarks, firefox sync, text files, and in figaro password manager (fpm2).
I've also tried to use bindwood in the past.
What I would like to do is merge all bookmarks and passwords into some solution that actually works either with tools available under Ubuntu, or with a browser-based tool (addon/plugin/extension) which works between between google-chrome/chromium, and firefox.
It would be ideal if there was an ability to send and store passwords encrypted (if not on my own server). Whatever the method, I need the ability to have import from existing sources. (It doesn't have to be pretty, just repeatable.)
It's possible that some things I've ruled out are now workable (e.g., xmarks broke for me at one point because I hit their bookmark limit for the server/account, and bindwood, firefox sync were firefox only).
I'm not aware of any cross-browser methods for synchronizing the passwords stored within the browser, but I find that the combination of KeePassX and Dropbox (or Ubuntu One) works well enough for my needs.
Lastpass works great for passwords (I use it with Chrome and Firefox, also on my Android device). XMarks works great for me for bookmarks (LastPass just recently acquired Xmarks, so there is likely integration coming). These tools work great across browsers, but also across platforms. Not sure why XMarks broke for you, but you may want to try again. I find it very stable and handles a huge amount of bookmarks for me.
For passwords as mentioned LastPass is really great.
For bookmark sync I use the Google Account sync with Chrome.