1. Tree Tabs: this extension lays out my tabs stacked vertically on the left of my window. I can fit upwards of 50 tabs in a window before I have to scroll the tab list. This is great for managing big research or documentation sessions without the squinting in Chrome. The APIs necessary for tree tabs are not yet in chrome, although there is some discussion now of a sidebar API.
2. Vimperator: this extension provides a very powerful vim-like interface, including a .vimperatorrc file. I don't use any more of the advanced features like that, but it is excellent for keeping my hands totally on the keyboard as I switch between Tmux splits, vim windows, and my browser. There are several vimperator-inspired plugins for chrome, some of which are passable. However, vimperator is a lot faster than Vimium, and the interface is more concise and vim-like. A big difference is the UI for opening links: in Vimperator, you press `f` to enter follow-link command mode. Each link is assigned a number by page order; you filter links by typing letters, and can follow the first link by pressing `enter`. So to submit this text form, I would press `esc` to return to normal mode from edit mode, then press `f`, and then type "rep<enter>" to filter links to reply, and then click it. It's rather natural, and easy to click the right link.
In Vimium, each link is assigned two letters (which are easier to type than numvers), but you can't filter links. There's a lot more squinting at the little labels to type the right thing. Plus, it's easy to fat finger the link text with no recourse.
