Are you searching for rental house very seriosuly? Then definety you should pop into all the websites which I have given in the list below. I have provided only few which came to my knowledge. If you can any new website give me the details.

http://www.rentinsingapore.com/

http://www.sg-house.com

http://www.singaporerental.com/ — only flats

http://www.singaporeexpats.com/

http://www.adpost.com/sg/homes_offices/244257/

www.share-accommodation.sg

http://singapore.gumtree.sg/f-Apartment-House-Real-Estate-condos-apartments-units-houses-W0QQSortZ3QQCatIdZ12

http://www.singaporepropertyexchange.com/

http://www.rentalandrealestate.com/

http://www.singaporeclassic.com/1_Singapore/posts/2_Rentals/10_Paying_Guests_RoomMates/

http://www.flatsdb.com/index.php?act=rent&code=view&ID=115940

http://easyroommate.com.sg/rooms/