What the heck is going on?  First, ladies golf god Annika Sorenstam and announces her retirement... then little Tennis dynamo Justine Henin says she's doing the same.  I don't get it.  Maybe I can get Annika's announcement (she's 37), but not Henin's... she's only 25!  Both of them are on top of their sport, or at least still darn close.  

It makes me remember some other former greatest that went out on top: Barry Sanders, Jim Brown, Pete Sampras, John Elway, Wilt Chamberlain, and Zinedine Zidane (if you ignore the headbutt) are a few that come to the top of the dome. 

Chime in.  What do you think?  Any others that surprised you by announcing their retirement?