Linkedin allowed 6 character passwords. If a user selected six random uppercase ASCII, lowercase ASCII and numbers, this would be the bit-strength:
print math.log(62) / math.log(2) * 6
35.72 bits
That's easy to crack. Also, keep in mind that humans don't select chars randomly. So the bit-strength of these passwords was probably closer to 20 bits. I cracked 2.5 million with an old cpu and JtR within a few hours.