OP

Usage: OP #<room> <nick>

If you are an AOP or higher in a room you can use services to op yourself or others. All of the ops in the room will see a notice telling them that you used services to op the person.

Example:
/msg chanserv op #conferenceroom webmaster

This is mostly useful when opping yourself. If you deop yourself for whatever reason, you can reop yourself without having to part and rejoin. Opping other people is usually easily done by moding them +o, but occasionally a bot or script will have problems with people opping others, then services can be used to avoid problems.