Here is a great plug-in that will help you to improve your email efficiency with no work on your part.  After a simple install, Xobni adds a handful of amazing features to outlook.  Xobni's handful of features include an email search functionality which is nothing new, but is not only incredibly fast and accurate, it is almost required for those of us using Outlook 2007 which is known to have inaccurate and in-concise search results or just stops working altogether.  Other functionality of Xobni is relating to attachments.  Click on a persons name and it will show in the Xobni panel all of the files you have exchanged between that person, in date order for revision tracking.  I have already saved tons of time with this feature alone, as I am always sorting by attachments to hunt down the attachment that was sent by a specific user.  Xobni has built in analytics, while not necessarily an efficiency saver like the rest of the features, sure is interesting to read.  Ever wonder how long it takes someone to respond, this'll tell you.  I can see a use for this, if you've ever tried to convince someone that so-and-so never replies to you or takes forever, now you have the statistics to prove it.  For the sales types, you can also click on a person and find out their Linkedin, facebook or Hoover company results quickly.  If you're interested, watch the video below and check Xobni out directly!