Hotpads is a free to use platform with a map based search interface. Hotpads.com was created in 2005 and acquired by Zillow in 2012. It allows users to fill out rental applications and pay rent online.
SpareRoom is a roommate matching service. Users post "ads" for what they're looking for and are contacted by other users who believe they match the description. SpareRoom is free to use but has "early bird" services for a fee.
Roommatch allows users to find rooms via a map based interface or to find roommates. Users complete a profiles with basic information, likes, interests and preferences. They are then matched to other compatible users.