Who can apparate?

[Cindy C.]

No: HPFGUIDX 27844

Early in GoF, we observe that Bagman and Crouch Sr. can apparate.  We 
also know that the adult Weasleys can apparate.  Ron tells us it is 
OK to steal the Flying Ford Anglia because his parents can apparate.  
We know Charlie eventually passed his apparition exam, and Percy is 
recently licenced.  I think Bill apparates to the Quiddich World 
Cup.  Dobby does the house-elf version of apparating several times.

But what about the rest of the adult HP characters, like Dumbledore, 
McGonagall, Black, Lupin, Pettigrew, Crouch Jr., Voldemort, Snape, 
Moody?  Are there any indications that any of them can apparate?  
Apparating surely would have been a handy way for some of the 
characters to travel at various times.  Black could have apparated 
off of Azkaban instead of traveling as a dog.  Lupin could have 
apparated to school instead of taking the train.  

It seems that apparating is, for some reason, a very underused skill 
in the wizarding world.  We are told that it is difficult and that 
people sometimes don't execute it correctly, so many people prefer 
brooms.  I think if I could created a fantasy world in which people 
could apparate, they'd be apparating all over the place.  I wonder 
why JKR didn't approach it that way.

Cindy