Ruby script for sha1 value count as it git does
Written just for fun on conversation http://juick.com/dmz/1374908 (Russian)

If you commit some files long time ago.
After that you or your teammates renamed it some times.
And now you forgot original file name, but still need to find a blob from some file.

Use the next command:
$ git-sha.rb filename1 filename2 ... filenameN

Output:
sha1_1
sha1_2
...
sha1_N

After that you can try:
$ git show sha1_N

And you should see the blob source.