Last year I was asked to serve as a referee for a journal for the first time. When I was asked, my adviser (I'm a 4-ish year grad student) said something to the effect of 'you can put that on your CV'. Now I'm updating my CV, and I'm not sure if he was serious or not. I know we're supposed to be honored to ask to referee a paper - but is that something that could, or should, be mentioned when applying for a job or fellowship? If not on a CV, then how? Or is it simply expected that people will serve as a referee at some point, and doesn't need to be mentioned? Would it make a difference if the journal is in the habit of only sending a paper to one referee as opposed to several? Thanks for any input.