Seems the BBC are trying their hand at creating a new kind of music chart, one which can track downloads, streams and buzz on an artist rather than measure units sold or shipped.
Its called the Sound Index and they're describing it thus:
"Every six hours the Sound Index crawls some of the biggest music sites on the internet - Bebo, MySpace, Last.FM, iTunes, Google and YouTube - to find out what people are writing about, listening to, watching, downloading and logging on to. It then counts and analyses this data to make an instant list of the most popular 1000 artists and tracks on the web. The more blog mentions, comments, plays, downloads and profile views an artist or track has, the higher up the Sound Index they are. So, the Sound Index is a music buzz index controlled entirely by the public."
You can filter the index for demographics and stuff, although as this is a beta test phase its a little limiting (only uk and us? pft.)
The main index is incredibly mainstream and foul so here's my filter for 27-39 year old males interested in indie and electronic music in the USA: "The Yankee Loner-Manchild Nerdo Indie-dex"