I don't know much about it but didn't DiS once use to be a label as well? How possible would it be to contact a load of bands (maybe with past or current associations with the site/label) and get them each to do a Sparklehorse cover?
Ideally there would be a physical copy but if that's not going to work then what about something similar to the Radiohead track where you had to make a contribution to The Royal Legion to download it?
Future of the Left (Falkous has posted on here in the past)
Worried about Satan
Youthmovies (I know they've split up but imagine if they got together one last time to record 'Hundreds of Sparrows'? How great would that be?)
and then you could have a mix of 'big' or 'small' bands depending on how it took off. I'm sure bands like '4 or 5 Magicians' would lay down a track, you might even get Radiohead onboard (they toured loads with Sparklehorse previously).
It would raise the profile of DiS, it would be a great way of celebrating Mark's life and would raise a bit of cash for the Samaritans or somesuch.
I know I might be rather naive... but surely it's got to be worth a try?
Any thoughts /ammendations/ whatever to the plan welcome from everyone else.