A recent Chromium build added a new internal page that lets you enable some advanced features:
"Tabpose is currently the only lab on Mac, tabs-on-left the only lab on Windows. about:labs should not be visible on the stable channel. Labs that were enabled on the dev channel should not be enabled on the stable channel."
Tabs-on-the-left is especially useful on widescreen monitors, while tabposé is a Mac-only feature that adds Exposé for tabs.
Both features can also be enabled by adding command-line flags to a Chrome shortcut: --enable-vertical-tabs for side tabs and --enable-expose-for-tabs for tabposé. After enabling vertical tabs using the command-line flag, right-click on a tab and select "use side tabs".