a hash is a unique checksum that can be used to verify the integrity of files. if the file is corrupt it will produce a different checksum. What the OP is asking for is for the checksums of our files to be published so they can be used to verify that a download completed successfully.
server can generate sums with idle power 24/7. no? Edit: it would take a while, especially when it hit the large files, but its a good feature?
We already have scripts that we run to do this against our current file set. It's not something we'll do often.