I'm becoming a violin teacher tomorrow (teaching my piano teacher) :) I was wondering... does anyone know of good songs/exercises to help with vibrato? I was thinking of Air on the G string. She always has a bit of experience playing, and air on the G string is slow and nice, so it'd be good for vibrato-training... I'm thinking that, anyway. Good idea? Got any more?

Yup - Air or the opening bars of Canon are quite good for vibrato practise. Also just sliding your finger up and down the string slowly but getting faster. There's lots of arguments about which finger is best to start with but second finger is the usual recommendation :)