I understand your challenge... service accounts can be hard to track. AD does not really provide a way to track logged on users. The only relevant info in AD might be the netlogon logs, where you can find logons and from what machine these originated.
I think you cannot get around checking each machine for not only running processes, but also remaining configurations of not currently running services, com+ components, IIS application pools,...
You can automate large parts of that using powershell or some combination of psexec, tasklist,... but first identify what exactly you want to check. Then post back in some scripting forum.
PS: You should really use one account per service and keep an administration of where it is used for what, the password, the access and privileges assigned,...
MCP/MCSA/MCTS/MCITP
