http://vo.do/ is
the biggest player ... but the
http://www.creativecommons.org homepage can direct you to many other sites as well...
for those not released under creative commons (cos the artist probably doesnt know about it) the pirate bays 'promo bay' is another way to find indie films legal for download... (please tread carefully here tho)
and for those that are just plain old;
http://www.publicdomaintorrents.com/ -- granted this isnt (usually) indie but theres stuff there that many have not seen... ...and its legal...
course the links (except creative commons homepage) are torrent centric but no worries since they are legal.... and ofc new material...
esp the legal kind... make great additions to ones shares on mx for those not torrent savvy...