So, what is the purpose of the balloon whisk? From what I researched, it's good for making air into bowls of egg whites and cream. For example, I saw my mom use it for cake batters and whipped creams. You can also use it for dry ingredients to break up large bits in flour, baking powder salt, etc. This can eliminate the use of a sifter. And I must admit, I love those and think that every kitchen should have one.
I have researched and came across some of the most interesting whisks. Some of them are used for certain types of preparations. So on that note, I found a site that should be helpful in providing knowledge about whisks. You can also make a purchase or find one you like and see if you can find it at your local department/cooking store. Check out Fante's "Which Whisk is Which?" for more information on types of whisks.
Little known cooking history fact: Did you know that Julia Child made the balloon whisk famous?