If you are an Apple lover like myself, it was hard to resist buying a subscription to MobileMe for its array of features. The whole time, I had an account with gmail that most everyone knew was my address. It became cumbersome to have to check both accounts throughout the day to receive mail from each account. I then found out there is a way to merge both of the mail accounts into one on the mail feature on the Mac.
This is a quick and very easy process. First open up mail located in the icon tray at the bottom of the screen.
Next from the top tool bar in the upper left hand corner click on Mail–>Preferences (or command , ). This will open the system preferences click on Mail in the top icon bar. See below:

Next, Click on the “+” at the bottom of the window:

Fill in your email name and password:

Mail will then add your account to the left hand side of the Preferences window. Be sure to name the account correctly within the Preferences window so you are able to distinguish how the accounts appear:

Mail will automatically add all of your folders from each account. I found this to be very convenient as now you can have your work and personal mail accounts all in one place.
If you use a different client let me know which one, I would love to know which ones are most popular!
Colin