Microsoft has written an article on how some things in Excel can be done without the use of macro's.
An interesting list. However I remember that back in 1999 when I use their approach to "Exclude duplicate items in a list" I found out that this was limited to approximately 1000 unique items.

This article describes some of the most powerful and useful features and functions in Microsoft Excel that remain undiscovered by users. For example, you may create a new macro to perform a calculation when an existing formula or function can perform the task. Or, you may create a new macro to perform a task when you can use an existing feature that performs the task.
Full article: http://support.microsoft.com/?scid=kb%3Ben-us%3B843504

(Via Spy Journal Excel Tips)