It’s the artist’s signature. You kinda have to look at it just right, but it’s his initials. Of course, it looks just suspicious enough that it was pointed out as a “satanic” symbol by at least one of the anti-rock preachers I was forced to listen to as a teenager.
Me too! (I’m listening to Rush right now.)
             
            
               
               
               
            
            
           
          
            
              
                Chingon  
                
               
              
                  
                    October 29, 2007, 11:56pm
                   
                   
              42 
               
             
            
              Ozomatli   uses a stylized oZo.
             
            
               
               
               
            
            
           
          
            
            
              Uhh…more.
Foo Fighters 
Van Halen 
Stray Cats 
Madness 
OK, I think I’m done now.
             
            
               
               
               
            
            
           
          
            
            
              Metallica 
Pennywise 
Black Flag 
Does Aerosmith  count?  It’s a distinctive symbol, but does have their name in it.
             
            
               
               
               
            
            
           
          
            
            
              Motorhead 
Psychic TV  (the cross at the top left of the banner bar)
             
            
               
               
               
            
            
           
          
            
            
              The Specials  always had the Two Tone guy  and checkerboard pattern.
             
            
               
               
               
            
            
           
          
            
            
              
 AskNott:
 
The band !!!  is pronounced “chick chick chick” or “ch’ck ch’ck ch’ck.” It was supposed to be the noise made into a microphone during a quick sound check. If you catch them on a different day, they might say it’s a paradiddle on a closed hi-hat cymbal, or some other thing. Hell, they probably don’t even remember where it came from. 
 
 
From here: 
! ! ! is pronounced by repeating thrice any monosyllabic sound. Chk Chk Chk is the most common pronunciation, but they could just as easily be called Pow Pow Pow, Bam Bam Bam, Uh Uh Uh, etc.
 
 
How has nobody yet mentioned the lightening symbol between AC and DC!?
             
            
               
               
               
            
            
           
          
            
            
              Peter Hammill  often uses the logo in the top right here .
             
            
               
               
               
            
            
           
          
            
            
              One that I can think of ('though I may be the only one on the board who still listens to this band:p):
Alien Ant Farm: http://www.cabands.com/bandimages/AlienAntFarm.jpg 
             
            
               
               
               
            
            
           
          
            
              
                phungi  
                
               
              
                  
                    October 31, 2007,  4:53pm
                   
                   
              53 
               
             
            
              Pearl Jam a few symbols, this one  being the most noticeable.
             
            
               
               
               
            
            
           
          
            
              
                yojimbo  
                
               
              
                  
                    October 31, 2007,  5:09pm
                   
                   
              54 
               
             
            
              As mentioned this symbol appears on all Iron Maiden Album covers. http://www.av1611.org/crock/images/ironms.jpg 
It’s a symbol of Derek Rigg’s though who is the artist and not the band itself.
             
            
               
               
               
            
            
           
          
            
              
                sqweels  
                
               
              
                  
                    October 31, 2007,  6:16pm
                   
                   
              55 
               
             
            
              Does Pink Floyd’s pig count?
             
            
               
               
               
            
            
           
          
            
            
              
 AndyPolley:
 
And it looks like this. 
 
 
Bless you. And it’s called the “Tri-ryche” if I remember.
             
            
               
               
               
            
            
           
          
            
            
              Negativland has their little house-casting-a-shadow symbol, seen here  on the cover of their album A Big 10-8 Place . They don’t like using the name of their band on T-shirts, so they use this symbol instead.
It’s also one of my tattoos!