One of my friends gave me the rest of her fancy French stretch mark gel that she used throughout her pregnancy, and she didn't have any stretch marks (and she's older than I am). I was skeptical that I would get any, and the ingredients weren't listed, so I didn't use it. Well, I got stretch marks.
Then I started using it like crazy hahaha. I might be delusional, but it seems to have lessened their appearance and I also haven't had any new ones crop up since I started using it two weeks ago. It's expensive and I wouldn't buy it myself, but it was given to me and it does seem to work. My friend was much more concerned with stretch marks than I am (and has more disposable income).
I can't remember the name, but I'll check when I get home later if anyone is interested.