I was recently composing a message in Gmail that mentioned "attaching a file" -- and then I clicked send by accident. Well, instead of sending an attachment-free email, I got the dialog box below. This is intelligent, thoughtful design. It's pretty simple to scan the email for keywords related to attaching text and popup an alert like this, avoiding an embarassing situation. This is why I love Gmail...
An UPDATE:
This functionality is NOT part of the core Gmail -- it is part of a Firefox add on called
There is another feature that is really interesting that allows you to auto-preview on emails by right clicking on them -- also very nifty but NOT part of the core Gmail software, yet.
