'Indie' has to be the most meaningless genre in the history of music. Nearly all other musical genres can be easily defined or recognised (e.g. funk, blues, soul, funk, jazz, dance etc) but indie means absolutely nothing.
It's really just been a means of marketing 'cool' pop groups since the mid 1980's.
Bands by indie albums are likely to encompass a whole range of musical styles; acoustic folk songs, songs with glam-rock guitars, jangly guitar pop (as pioneered by 1960's bands like the Byrds), a quiet verse/distorted chorus sound (developed by Pixies made popular by Nirvana, Wannadie, Blur's woo-hoo, Feeder etc), a symphony pop song (arranged with violins), songs with a disco drumbeat. Verily, there is no such thing as indie!
It's ridiculous that bands like The Scissors Sisters are considered 'indie'. They are no different to the Bee Gees; they are all over XfM and Virgin yet when did either station last play the Bee Gees? Similarly, The Feeling are, to all intents and purposes a mid-70's easy listening/soft rock band (not necessarily a bad thing), yet they too have been embraced as a modern indie band.
In the 80's, indie was supposed to be a kind of intellectual and reflective alternative to mainstream pop music but then in the 90's along came brainless, bigoted idiots like Liam Gallagher in bands who were bafflingly marketed as indie!
If the Beatles first appeared in 2006, they too would be considered an indie band, yet they have never been called one coz indie wasn't a known term in the 60's.
And that, frankly, is all I have to say on the matter!