Indie, huh? My best friend is obsessed with Indie music and he knows about every band.
I am not going to take all of his music, but here are a few bands:
Islands, Destroyer, Liars, Suburban Kids with Biblical Names, Modest Mouse, Ugly Casanova, The Unicorns, Imperial Teen, Enon, Clem Snide, Silver Jews, YYYs, Deer Hoof, The Octopus Project, Peaches, Nick Drake, Test Icicles, Do Make Say Think, The Cornn 'Gangg, Matt Costa, !!!, John Lennon, Vashti Bunyan, The Get Up Kids, Part Chimp, Of Montreal, Stereo Total, The Sea and Cake, Holopaw, Pavement, Diplo, The Fiery Furnaces.
Here are some of my bands:
The Rasmus, Linkin Park, The Knife, Mew, Snow Patrol, Placebo, She Wants Revenge, PMMP, Kimya Dawson, Zeraphine, Yokko Kanno, Yeah Yeah Yeahs, Tegan & Sara, Sum 41, The Subways, The Strokes, The Killers, Interpol, Incubus, Static X, Spoon, Sneaker Pimps, Smile Empty Soul, The Servant, Rock N' Roll Soldiers, Seether, Rooney, The Rapture, Her Space Holiday, Him, Hinder, Hot Hot Heat, Hard-Fi, Evanescence, Entwine, Enon, El Guapo, Defualt
Mine are more Alternative. I gave you a lot of the "Main Stream" (but not all of them are main stream) bands in my list, that way you can find their songs on P2P clients. I hope you and your friends enjoy it.
[Edit]
Here are some more from another friend.
José González, Lovage, Kid Koala, Madvillian, Nostalgia 77, Wolf Parade, Jana Hunter, Diplo, Beat Happening, Animal Collective, Modest Mouse, The Dirty Projectors, Liliput, Moldy Peaches, Devendra Banhart, The Blow, Caribou, Silver Jews, Kimya Dawson, Seu Jorge, Yves Montand, Mulatu Astatqé