About a year ago when Google changed the Gmail interface and added a lot more customization options and themes, they also made it surprisingly hard to find the Gmail Invite button, so much so that it's not an uncommon occurrence for me to receive requests from people asking me to send their friends invitations to the popular free Web email service.

Thing of it is, the option is still a part of your Google Mail interface, it's just ridiculously subtle, to the point where most people -- possibly you included -- have no idea it's there. Indeed, the only reason I stumbled across it was because I like to click and experiment, learning what buttons do what, where things are hidden, etc.

The key button is adjacent to the "Chat" button and they're both on the lower left of your window. But don't take my word for it, let me show you...

On your Gmail home page, on the left side:

It's the ellipses (three dots) that exposes the invite box. Click on it and...

Enter an email address and click "Send Invite" and it quickly shoots off an invite to that person. The only visible indicator you'll get is that your "50 left" will go down by one:

Of course, in most countries they can just go to the Gmail home page and sign up, but it's still fun to invite someone, right?

Oh, and that little cartoon talk balloon graphic? If you click on that it reveals the Google Chat feature:

My favorite part of this is unquestionably the ability to make phone calls and chat with people on your computer without worrying about Skype, etc. You can see it above: "Call Phone".