I've been tracking comp data for our rentals via Rentometer.com roughly quarterly when I remember. I'm however now about to give up on Rentometer. The last time I checked was August and the data I looked up today is completely unchanged for 3 of our 5 properties.
Here's the January 2016 data :
Properties A, C & E are exactly the same in all points compared to August and that can't be valid. I know for a fact that rents for the areas that A & E are in are going up pretty fast.
I'll probably switch to using Zillow.com and/or Craigslist..com Zillow just gives their Rent Zestimate which is just a single dollar estimate of rental value. But it doesn't seem to handle the mult-plex properties too well since it doesn't seem to cite rents for individual apartments. It works well enough for the single family homes though.
Zestimate numbers today for the SFH are :
Plus I can get a lot better filtering on Craigslist so it will be better. It takes a lot longer to do such comp checks on Craigslist however which is why I've liked to use the simple / easy test on Rentometer.