I love my .Mac aliases, but Apple really dropped the ball on allowing users to add unique names to each alias in Mail.app. By default, a message from a .Mac alias doesn't have a sender name or anything - the sender is simply the alias itself; kinda ugly if you ask me.
Fortunately, MacOSXHints has done it again and discovered that you can simply edit Mail's preference file to add a unique name for each alias. Their post recommends using Property List Editor, but on my PowerBook the file opened in OmniOutliner Pro, which made finding the right part of the file to edit a breeze.
No matter how you do it, this simple trick makes those .Mac aliases a bit more valuable and aesthetically pleasing. However, Apple really should listen up here and create an easier way to do this for the typical .Mac customer.