How to find double entries - Mailing list pgsql-sql

Hi,

how can I find double entries in varchar columns where the content is 
not 100% identical because of a spelling error or the person considered 
it "looked nicer" that way?

I'd like to identify and then merge records of e.g.   'google', 'gogle', 
'guugle' 

Then I want to match abbrevations like  'A-Company Ltd.', 'a company 
ltd.', 'A-Company Limited'

Is there a way to do this?
It would be OK just to list candidats up to be manually checked afterwards.


Regards
Andreas