RBLs in use

["Paul S. Brown" <pol () geekstuff co uk>]

I have been asked to find out what DNSBLs are in use so my employer can see 
what the incidence of its being blacklisted is and how much impact this is 
likely to have had on their business.

What DNSBLs are being used by the various agencies represented on NANOG and 
how much weighting do you give them. Are there any DNSBLs you would 
completely ignore due to data quality issues?

Thanks

Paul