Tabbed browsing is a blessing and a curse. It certainly helps with multitasking, but only to a point. I sometimes find myself lost amid a sea of Chrome tabs. Thankfully, there is Video Controller, a Chrome extension that adds YouTube controls to the toolbar.
Install the extension and you'll see a small button (with a purple play icon) gets added to Chrome's toolbar, to the right of the URL bar. Now, if you are listening to music on YouTube, you can stray from the YouTube tab and still have access to play/pause and volume controls. Just click on the purple play button to reveal a small control panel. Without leaving your current tab, you'll be able to pause, mute, or otherwise adjust the volume of the track playing. And if you are listening to a playlist, you can use the fast-forward and rewind buttons.
If you have more than one YouTube tab open, the Video Controller will show multiple listings. To close a YouTube tab, just click the small X to the immediately left of the band and track name. And if you don't have any YouTube tabs open, you can use the Video Controller button to launch a new YouTube tab.