Time was when getting on the playlist of a major radio station was the dream of every up and coming band. Now it seems TV soundtracks have become a far more crucial platform in reaching a mass audience.

Famously, Snow Patrol broke America almost overnight when their song Chasing Cars was played during a climatic, emotive scene of hit hospital drama Grey's Anatomy. That particular episode, the season finale, was watched by 23.5 million people, giving the band's profile a stratospheric boost. Over there, the promo for the song was actually re-edited to include clips from Grey's Anatomy. A cheesy move, but a hugely effective one.

Less well known is the case of James Blunt, who was practically unknown in America until You're Beautiful was used to soundtrack promos for the 2004 Olympic Games on mainstream TV channel NBC. The resulting blanket coverage created a formidable word-of-mouth buzz, eventually leading to a monster hit.

This is nothing new, of course. Back in 1998, Green Day's career - then flatlining, following dismal sales of their Nimrod album - was instantly revived when their ballad, Good Riddance (Time Of Your Life), featured in the final episode of Seinfeld, watched by a vast TV audience of 76 million. Billie Joe Armstrong and co woke up the next morning with a colossal new mainstream fanbase.

Adverts, too, have always been instrumental in launching careers. Most recently, US folkie Devendra Banhart has been given unprecedented exposure thanks to those ubiquitous Orange ads ("People are good together"). But the difference with TV shows - especially dramas such as Grey's Anatomy - is that viewers have an emotional connection with the characters, which in turn invests the track with a profundity and resonance it might not otherwise have had. Breathe Me, a haunting piano ballad by Australian chanteuse Sia, certainly benefited from this kind of cross-pollination when it was played over the spine-tingling closing sequence of Six Feet Under.

Increasingly, record companies are recognising this. In a sense, getting on TV shows is easier than getting on radio playlists, since there's often a greater willingness to take a chance on something new. Gary Calamar, who supervised the music on Six Feet Under, explains: "The problem with radio is a concern with being safe. It's all about following trends. TV and ad people are much more willing to take risks than radio programmers are. There's actually a preference now for music that hasn't been heard in a lot of other places."

Maybe. But it's also noticeable that most of the artists to have benefited from TV exposure - Snow Patrol, James Blunt etc - are of a decidedly middle-of-the-road stripe. The acts that work well on TV dramas tend to be inoffensive, tuneful, faintly melancholy. It's not like you're going to hear The Mars Volta over the closing credits of Desperate Housewives, for example. So are we really witnessing a brave new dawn of fearless musical experimentation - or is this just one rigid, conservative medium being supplanted by another?

What are your favourite TV soundtrack moments ever?

To get you thinking, here's the slightly dodgy US version of Snow Patrol's Chasing Cars, complete with gratuitous Grey's Anatomy cutaways.