Here's a template for a expressing interest in working for someone:
Dear Prof. _____,
I am a [undergrad? research assistant?] at [school/company], and I am applying to the _______ PhD Program (for admission in Fall 2014). My main academic interest lies in ___________, and I am intrigued by your work. I was wondering if you would be willing to consider me for a position in your lab if I am admitted to the program.
My CV is attached. Briefly, I graduated from _________ in [year] with a degree in [subject]. I am now [working on something relevant]. [describe research projects in a few sentences]
I read with fascination your recent report on [???], [provide some thoughts].
Please let me know if you would consider taking me as a grad student. Thanks for your time, and I hope to hear back from you.
Thank you.
Yours sincerely,
XXXX
Notes:
- Be sincere! Don't fake interest in working for someone just to get accepted into a program! I mean, how bad will it look if a faculty member speaks up for you during the admissions process, and then you change your mind about working for their lab?
- Timing: Don't do this too soon: you want the profs to remember who you are. On the other hand, don't wait till the last minute.