Thanks for all the comments,
This has made me want to do this project.
Just to update further, I have just built by own loft conversion and where I have fitted the new stairs has left an area approx 4' x 2' which cant be used. I plan to put some doors on this area half way up the stairs to have amp, media extender, projector, etc for the bathroom and also the home network router,etc. As far as ventillation goes I can Do what i want. It is against an outside wall so I can add an extrator fan or would just a vent do the job.
Because the projector would be linked to the media centre I can watch TV, Play music, Browse photos, etc all in the bath.
Im not sure why I would want to do all of this as I normally take a shower.
I think I am mad!!