Anyone who knows me knows I really stress being able to play a computer like an instrument (and if you think you can, then prove it). Us geeky types are in front of our computers for 12+ (often 16+) hours per day, so every loss of efficiency translates into a huge cost in time -- and time is the most precious asset of any hardcore entrepreneur.
One thing I've done is to really customize my Google Apps email pane, with functionality from Rapportive (THANK YOU for the Highrise raplet, guys!), Boomerang, TwitterGadget, Gmail Auto BCC, Labs custom keyboard shortcuts, Send & Archive, etc. I've also found some great Chrome extensions, including 1Password, Bit.ly, Awesome Screenshot, and by far my favorite -- a Basecamp text auto save extension that saves what I've written in Basecamp when the page is closed.
Here's what my email pane looks like, with a detailed video below that walking you through how I use everything.
My favorite feature? The awesome picture of my wife, of course! If I'm going to be looking at email for hours each day, I might as well make it enjoyable! I just replaced the standard Gmail logo with a custom image.