Neat ideas, but:

• How often are they going to get used (I've been a user 5 years today and I've never used any of the existing shortcuts mentioned)
• You're reimplementing what a lot of modern browsers do in their location bars already (more an argument against the "makes the search box smarter")
• While you're kitchen sink-ing you'd need thott:// to lookup World Of Warcraft items on http://www.thottbot.com/ :)

</Devil's Advocate>