Hey, have you heard about the newest Firefox Add-On, Ubiquity? It allows you to do lots of different things without leaving the Ubiquity window.
You can:
add things to your Google Calendar
search Amazon.com
search Answers.com
search Ask.com
search Bugzilla
calculate mathematical equations
link to Wikipedia
add a map
get a tiny URL
Twitter
search YouTube
You can put any of it into an email, which makes it interesting for me. What Mozilla says is: "Enable on-demand, user-generated mashups with existing open Web APIs. (In other words, allowing everyone–not just Web developers–to remix the Web so it fits their needs, no matter what page they are on, or what they are doing.)"
An interesting idea? I think so, but then, I'm a sucker for most anything that can make my life easier.