Gmail's got a new option in its labs section that lets users insert images directly into their e-mails, and not just as attachments. This has been something you've been able to do in standard e-mail software for ages, but Gmail's way of handling them for the last five years has simply been to stick them on as attachments that show up in the bottom of your outgoing message.
This wasn't the worst way to view images, but if you were using Gmail to put together a short photo tour of your travels, or a family newsletter, it's come up short compared with software e-mail clients like Outlook, Thunderbird, and Apple's Mail that offer much richer creation tools.
Now, when you want to insert an image into your e-mail you can either upload it from your computer or grab it from a URL (like you're able to do in Google Docs). It sticks it right into the message where it can be resized and aligned to fit in with the rest of your message. Gmail warns that while going the URL route is easier, if your recipient's using Gmail or some other Web mail service they'll have to click on the "display images below" link since it doesn't load them to keep spam at bay.
My own personal request is for Gmail to offer the same kind of simplicity for videos. Does a friend or family member have a video they want to share via e-mail? Great, but it probably won't fit as an attachment. If Gmail were to build in an integrated YouTube uploader, I'd be in heaven.