Heya Tigger Tiger,
At this point, it sounds like you've already submitted your application to the medical schools. Since you're Canadian, and you live in Vancouver like me,
I suspect one of the ones you've applied to is UBC.
Let me just say that most medical schools are running around frantically trying to arrange interviews for each of the candidates. Sending a letter of interest now will not be particularly beneficial, as it will likely be shelved into your file, and not read.
If you were to write a letter of interest, I suggest doing that after the interviews are completed, but before the admissions committees have met. Right now, at this stage of the admissions game, there's nothing about yourself you could write that you couldn't express in your interview.
Letters of interest, in my opinion, are used to inform the committee of any interesting details you feel are relevant that you've encountered since the interview time. ie: you've just been awarded an academic scholarship, you've taken a job doing medical research, you have started an interesting and engaging volunteer position, etc.
People say that sending a LoI shows interest in the medical school, but I wouldn't send a letter if that was all I was going to say; medical schools already know that you're interested. If you weren't, you wouldn't have applied.
If you have further questions, please drop me an e-mail.
Ian
UBC Medicine Class of 2003
www.geocities.com/mdpremie