[0] https://github.com/philc/vimium
[1] http://www.askvg.com/how-to-enable-new-side-tabs-feature-in-...
With it, you could implement something like the old Side Tabs feature (that you mention), which was removed from Chrome due to "the complexity of a tree-style interface in terms of usage is beyond what most users need or want, and in terms of implementation is more than passes the cost/benefit test for building into Chrome natively as an option."[1])
[1]: https://code.google.com/p/chromium/issues/detail?id=344870#c...