Hi,
These websites won't have all the logo's ever made but... they have a lot!

'AllTheLogos.com is an online database of logotypes and logo design. This includes more than 90,000 companies and organizations brands logos, team sports logos, countries flags and insignia as well as signs, general usage logos and more.'

I used to be able to download even the vector illustrations of the logo's but I'm afraid they had to stop it. Still its a nice resource or even inspiration. 

http://www.allthelogos.com/

Here i found the vector downloads of logo's
http://brandsoftheworld.com/