So far, we’ve seen or heard the following:
1) In Rose, the Nestene Consciousness quite clearly shrieks the words “Bad Wolf!” as the Tardis is revealed (the Doctor says it has recognised the Tardis as “superior technology”).
2) In The End of the World, the Moxx of Balhoon mentions to the Face of Boe that they are facing “the Bad Wolf scenario”.
3) In The Unquiet Dead, psychic scullery maid Gwyneth tells Rose that she’s seen the darkness in her mind — “the big bad wolf”.
4) In Aliens of London, a young boy tags the Tardis with the words “BAD WOLF” in white paint.
5) In World War Three, the American newsreader is identified as Mal Loup — at least, on the website version (requires RealPlayer). I didn’t see any such identification on the broadcast version.
6) In Dalek, the call sign of Van Statten’s helicopter is identified as “Bad Wolf One”.
7) In The Long Game, The Face of Boe announces his pregnancy on Bad Wolf TV. </i>
8) In Father’s Day, the words “BAD WOLF” reappear in graffiti form — this time on a poster promoting a rave (Energize, to be held on 20 November 1987).
I missed the reference in The Empty Child, so I'm still trying to find that one out. Fascinating to try and find each week, and rewarding careful viewing. As to what it all means - I have no idea.
But I can't wait to find out.