Colibri is a browser without tabs. It offers two replacement concepts:

• Links, which is essentially a list of interesting links. Instead of opening a new tab, you would place the existing one here.
• Lists, which helps you grouping links.

I like the idea a lot and think that it has a lot of potential - I agree that the idea of tabs needs overhauling. However, I disagree with the implementation so far. Colibri lacks many basic features, which I would find acceptable in an MVP.
But their key features, Links and Lists, are hard and not intuitive to use, and the current feature set for these features are not very satisfying, considering that this is supposed to be the unique selling point of this browser.

Nice idea, needs more work.