GMail address suffix
Do you know that you can use any suffix with your GMail address as long as it’s preceded with “+” sign? So if your address is johnsmith@gmail.com, you can tell people to send emails to johnsmith+friends@gmail.com and it would still reach your mailbox. Now you can create several filters using “To:” field and your mails would be in order. When you’ll be signing to some online service, for instance a forum, you can use johnsmith+forum@gmail.