My Master and I had an online relationship for several month, almost a years before we decided to meet (finally!). During this time he would set me task such as writing stories for him and e-mailing them (or posting them on a site we both had an account on) by a certain date with him choosing the settings and the plot of the story.
He would also ask for pictures, sometimes he would set a place they had to be taken (i.e. on my back porch, in a public bathroom, in a park, ect.) sometimes he would just say something like, be naked, or wear a red bra and panties, or dress up.
Also he would occasionally email me and tell me to do something by the time he got online and he would give me an estimate time. This mostly consisted of having a certain number of climaxes. Or taking a shower and fingering myself while bathing. (I usually only masturbated after I had went to bed.)
These are just a few ideas that I particularly liked, You could also have her start a blog somewhere and write something everyday on a certain topic so You can read it. Or have her email a few paragraphs of her thoughts on Y/your relationship or other topics.
I hope my ideas help You.
Sana