The number of rentals available in Milwaukie is fairly scarce right now, if you find something you like, move on it quickly!
http://www.trulia.com (Rentals Section)
http://www.zillow.com (Rentals Section)
http://www.realtor.com (Rentals Section)
Between all of those, you will get a very clear picture if you can find what you are looking for. Good luck!