Google Chrome Pinned Tabs
This has been in Chrome for a while, but I just noticed it because of Firefox’s App Tabs. You can right click a tab and “Pin” it. To make it open that way every time you start Chrome just requires modifying the Chrome application shortcut.
Update : Considering how fast Chrome updates, this is already old. Now all you have to do is pin a tab, and it will stay pinned. Modifying your shortcut no longer does this.