Just about every host has restrictions on the allowed content on their servers in their TOS or AUP. I mean the regular stuff like no porn, no insulting stuff, no IRC, etcetera.

What I want to know from some existing hosts is :
Is there special software to monitor your accounts, or can this be done with standard unix commands?
What do you use, how do you use it ?
Is it a manual process, or is everything monitored automaticall, and do you receive notifications by email.

I am planning to go dedicated in the near future, and need to know how to enforce my TOS.

The best way to do this is just keep a watch over the server. View all the processes running on it with a 'top' or 'pstree' to see all the programs running on the server. You would be able to cache irc bots or strange programs running many times with these. Keeping tabs on bandwidth will also help. Other than monitoring the server itself there really are no ways to know the exact content of the sites - unless you actually go to all your clients sites.