Here some other frighten things about double and possible double spends:

My coins were stolen in the middle of the night and I don't know how
http://www.reddit.com/r/Bitcoin/comments/27jsy3/my_coins_were_stolen_in_the_middle_of_the_night/


GHash.IO & double spending
http://www.reddit.com/r/Bitcoin/comments/279sex/ghashio_double_spending/

Selfish Mining: A 25% Attack Against the Bitcoin Network
http://bitcoinmagazine.com/7953/selfish-mining-a-25-attack-against-the-bitcoin-network/