I notice that perhaps most US graduate programs require non-native English speakers to get a certain mark on the TOEFL. Is this requirement typically waived for students who completed their bachelors degree in the US before applying to a masters program in another school also in the US?
I was in this position - as an international student applying to US graduate programs after being a US undergraduate. I contacted the graduate programs I was applying to to ask if they would waive the TOEFL requirement, and they all did (i.e. I didn't have to retake it). I heard recently that the requirement for a waiver (for my current university at least) is for an applicant to have been at a US university for four years.
My backup plan if the graduate programs had seemed unsure about a waiver was to call someone on the phone and essentially demonstrate that I am fluent in English.
(The TOEFL is expensive!)