Sorry, I was quite busy these days and didn't come here for a long time.
I think your file is strong except the relatively low GPA. You GRE Verbal is fine since you are applying to science/engineering.
Some information about me is the following:
GPA: 4.90/5.00, Major in Applied Math, first class honours, graduated in 3 years.
GRE general: V 710, Q 800, AW 3.5
GRE math subject: 900/900, Percentile 99%.
Honors: President Research Scholar; Full Undergraduate Scholarship.
Research Experience: one year research under the President Research Scholarship; Aug 2008 - Present: working as research assistant and in math department. Also, I have worked as a teaching assistant for 3 semesters.
Publication: 2 submissions to top journals on optimization (1 is under revision), 1 working paper and 1 proceeding.
Reference letters: all from my department.
I don't know how important the statement of purpose is... My English, especially the writing, is not good. I think it is tough for international students to get into top universities. So, I am very nervous... Any comments are welcome. Thanks.