Spam (un)blocking

[Adam Jacob Muller <adam () gotlinux us>]

Hi,
I'm a network operator at a small hosting company that has about a /20 
slice of IP addresses. Recently we have suffered a few break-ins (and 
some fraud) which caused a large quantity of spam to find it's way onto 
the internet.
This has resulted in some of our network space being listed in several 
DNS blacklists, and being blacklisted by individual ISPs.
So my question is this.
Firstly, what is the best way to remove myself from each of these 
blacklists, if there is anything aside from going to each one 
individually and saying "i'm not spamming anymore".
Second, is there some way to mark my block of addresses is owned by 
responsible responsive system administrators.
We have tech support on duty 24/7 and abuse complaints are dealt with 
in a timely manner, so I am wondering if there is a way to communicate 
our willingness to help in the fight against spam.


Thanks,
Adam Jacob Muller