Online Music Charts 

 Official Charts 

• UK - top 100 singles & albums, top 40 downloads
• UK - BBC - seems to be more official than the above link...
• USA - Billboard - wide range of charts available
• Australia - ARIA - singles, albums, downloads, genres etc...

 Other Charts 

• CMJ Radio Chart (USA) - compiled from alternative radio stations
• MySpace (unofficial) - the most played tracks on MySpace
• When Killed Like Roosters - very independent, and selective