From "The Parting of the Ways" -
I love this scene for so many reasons. When I first started watching "Doctor Who," I was in a similar place in life as Rose was. I didn't have a job, I lived at home, I felt like I didn't have very much going for me, people around me were never very happy so that rubbed off on me and I was never very happy - and then I was introduced to this wonderful, fantastic, amazing person who did wonderful, fantastic, amazing things and shared his experiences with his friends. It was something I needed when everyone else around me was dripping with cynicism and negativity - it was something good and something to be happy about. And I felt like I could do something to change my own fortunes - or at least the things I was doing were going to lead me somewhere good eventually. Every time I watch "The Parting of the Ways" and see this scene, I think of that time in my life - how much the Doctor changed my life much the way he changed Rose's.
Also, Rose is just awesome in this scene. And it sets up fantastic things to come.