There is concern among bitcoiners, that pool with >50% power can exploit the network with double spending transactions. I think that someone should make a service for monitoring blockchain forks and double spending attempts. I'm pledging 50 BTC for such service; if you are concerned with this problem too, add up your pledge.

To receive award this service should provide at least

1) Real time list of blocks, including orphaned ones
2) Real time list of transactions with double spend attempts