Okay, before I start, I just want to say that this is not a thread where I mean to gloat about how this happened, etc. but I make this after reading about everyone freaking out, etc.
Anyway, you may notice that I had a thread here a few months ago about how I had a bad GPA, and if I even had a chance at some of the lower UCs:
My SAT also wasn't outstanding (2200).
But, as people have said, time and time again, it is passion that counts. For example, for me, one of my huge passions is running. I've been running for a few years, but I've devoted tons and tons of time to it. Not just cross country in the fall and track in the spring, but in the off season such as the summer and winter, I would run close to 50 miles per week and basically ran almost every day (out of a month, I would maybe not run 1-2 of those days). I know tons about running such as top athletes, training styles, coaches, races, etc. So to put it this way, it was one of the things that was huge in my life (and something I devoted a lot of time to), and that is what you need to find: a passion that really drives you in life, not something that you just "do" to put on your college application. I did tie in running with one of my essays, and as cliche as it might sound, your essays really do have to be from "the heart" and the readers will know if you are really passionate about something. For me, if I do go to Stanford, I'll just be able to walk on to the team (Stanford is very, very good) because I would like to keep running in college.
I didn't do that many extracurriculars but I did ones that I really liked and ones that really meant a lot to me. If you really like something and feel passionate about it, Stanford will realize it and definitely take that into consideration. Another example for me was the AP US History class I took in 11th grade. I took more science classes/engineering ones, but this class was one that made a huge impact on me. I barely got an A (studied like crazy on the final exam), but I realized that that wasn't a huge thing about the class.. it was just that I had learned SO much throughout the whole class that I really felt I took something away from it besides just a letter grade. Again, passion is what counts here.
The next thing is apparently huge upward trends help a lot. I don't want to post all the stats here but if you look at the "chances" thread, my GPA was terrible sophomore year and I did manage to raise it junior year by working a LOT harder.
The last thing is that even if you feel there are a ton of people overshadowing you, you should still apply. I seriously thought (and I was) a huge reach at schools like Berkeley and UCLA but I gave it a go at Stanford anyway.
I don't know if this helps at all, but I just want to say not to give up, and even if you don't get in, there are a lot of schools out there. If you guys have any questions feel free to ask.