DAB has this, but a lot more besides. There was some talk of the BBC actually outputting the song lyrics via DAB, but there were some copyright issues and the idea was canned.

I don't think that RDS refreshes often enough to actually do this though - pity.

Paul.

Paul Haigh, Reg. 4120
(mk1) 6GB, Blue, 00254
(mk2) 12GB, Red, 00357