There is a nice simple new feature in the Gmail Labs. It puts a small number in front of favicon to let you know how many unread messages you have without needing to pull up the screen or click on the tab.
"When you’re visiting sites other than Gmail, it’s easy to find out how many unread messages are in your inbox by glancing at the title of your Gmail tab or window. However, if you have a ton of tabs open, or if you use Chrome’s “Pin Tab” feature that hides everything except the tab’s icon, it can be tricky to figure out without switching tabs.
If you’ve ever found yourself in this situation, you may like the new Unread message icon we just added to Gmail Labs. It embeds the number of unread messages you have right into the Gmail icon itself, like this: