I just created some very simple extensions for Chrome shortly after I taught myself how to create extensions.
As I said, they're VERY simple, but I find them useful, so I figured it wouldn't hurt to share them.
Each extension is a simple lightweight extension that adds a shortcut button to your browser for quick access to your history, extensions, or downloads. It either opens a new tab, or switches to the respective tab if you already have it open in a tab you're not using.
You could nearly accomplish the same thing if you made a bookmark, but this assures you won't open multiple tabs and I like to keep some things separate from the bookmarks bar.