This is a list I gathered over the years:

AdminServ,ALIS,BotServ,ChanFix,ChanServ,FunServ,GameServ,Global,GroupServ,HelpServ,HistServ,HostServ,InfoServ,LimitServ,MemoServ,N,NickServ,OperServ,Q,RootServ,SaslServ,SeenServ,SpamServ,StatServ,UserServ,X