Many are not listed other than via specific Hash websites.  Some generally available are

YAHOO 
Some are public and you can view them without subscribing, others you must subscribe to to be able to see anything.

URL:  http://groups.yahoo.com/search?query=hash&submit=Search

will give you a list of lists that might keep you busy for days 
Two from the list
Eurohashing- http://groups.yahoo.com/group/eurohashing/  you have to join toview
Gold Coast Hashes- http://groups.yahoo.com/group/goldcoasthashes/ you can view instantly

MSN
From http://groups.msn.com/ and do a search on Hash, Hashing etc.,  and endless options. 

ORIGINAL HASH List at USC (mainly USA particpatants)
now ancient bit of technology but you can read a mirror of the bullshit courtesy  BBBB
Sunday - Monday - Tuesday - Wednesday - Thursday - Friday - Saturday
Last Sunday - Last Monday - Last Tuesday - Last Wednesday - Last Thursday - Last Friday - Last Saturday

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