Rental unit rates by town?

[Dave Mosher]

I am wondering if there is a place online that will show the average monthly rent rate of an apartment, single family etc., by town and even better by neighborhood.  I am looking for my next deal and I want to make sure that I am factoring the rent correctly or at least will be in the ball park.  I looked at apartments for rent but not every town has an abundance of for rents on the market.  Thanks,

-Dave