Featured Floor Plan Provider:

The basic house plan search feature searches through 21,000+ floor plans and has you specify the number bedrooms, bathrooms, number of floors, garage size, and maximum width/depth.

The advanced search feature even more options. One search criteria I found particularly interesting was the ability to only show the matches with a "Photo Gallery" so you can see actual pictures of designs meeting your criteria. Some of the photo galleries contain numerous photos of the interior spaces as well.