A pretty good course in how to do a crossover, Jack hitting on Sarah Jane and all. (And really, Lis Sladen is gorgeous, so he cannot be blamed. Though his curiosity about Luke was REALLY DISTURBING, even for Jack; I'm a little stunned RTD went there.) When the Doctor and Rose were doing their long run towards each other, I said, out loud, "If a Dalek shows up and shoots her --" and then a Dalek showed up, and I figured she was going to fling herself in front of the Doctor and be exterminated saving his life and the internet would EXPLODE.
I'm putting my prediction on the record: Davies is cross-overing every headliner he's worked with on the show and its spin-offs. The Doctor is regenerating in the middle of a region of space that's temporally out of sync with the rest of the universe.
Ergo: Christopher Eccleston.
PS. YOU BETTER NOT HURT SARAH JANE, DALEKS. I WARN YOU.