Basically I needed this and couldn't find it, so I made it.
It adds an extra selection to your context menu (when you right click on a page) called "Wayback Machine" that opens a new tab with the most recent archived copy of the current URL from the internet archive's wayback machine.
Installation is straight forward. Download both files, put them into a folder, drag the folder into the extensions page.
I'd add it to the Google Chrome Store but I'm not paying them $5.