Name all your windows and manage where your new tabs go by the names of the windows!
Give your chrome windows names, and then for any tab, choose which window you want all new tabs to go to! So make a new window called 'Gmail', and tell your gmail tab to send all new tabs to this window. Your gmail window stays neat and tidy and all the links you open from gmail don't get mixed up with links from other sites. Do the same for Facebook, Twitter, and any other sites where you don't want to mix up your tabs!
Also includes right click open-tab to send a new tab to any of your named Windows!