Administering large elgg sites

Hi,

I'm developing an elgg network for my company that anticipates over 20,000 members.  There are several issues I'm concerned with.  The available admin tools do not seem robust enough for the kind of issues we expect.   I'm sure other large sites have wrestled with this issue. For example, in any large community, one expects to have people who abuse the system. How do large sites handle that?