Send from Omnibox is very close to what I was looking for, only it opens the gmail page and requires you to submit the email from there.
Compose an email without leaving the page.
Compose an email just by typing in Chrome's address bar.
Emails are started with a "." and a space. For example:
. matt@example.com sub What's up?, I thought you'd enjoy this picture: http://bit.ly/6kEfZ0
will open a compose window (using mailto) to matt@example.com with the subject "What's up?" and the included message.
Define a custom shortcut for someone's email by typing
. set m, matt@example.com
and then "m" can always be used instead of matt@example.com.