I don't get exceptionally large when I get pregnant - rather than going out, I tend to carry really long in my torso. That keeps me from getting all-over stretch marks, but I did get a couple near the end of my pregnancy with Pickle where her head was sitting (I was pretty lopsided and carried all to the left).
Those two stretch marks had gone away by the time I got pregnant this time, so I wanted to try and keep them away. I invested about $11 in Burt's Bees Mama Bee Belly Butter (LINK).
I started using this around 26 weeks or so, when I popped. It's got a great smell (as Burt's Bees is so great at doing!), and isn't super-greasy. It's mostly just like a thick hand lotion.
It worked great for the first three weeks or so, but I've still developed a couple of small stretch marks in the same area where I had them with Pickle, as well as new one. I don't know that there was much the belly butter could have done to prevent the ones in the area that I had before, but the new ones are a little less encouraging.
All in all, this is one of the cheaper belly butters on the market, and it may be doing SOME good, but I don't know that I'd purchase it again.