Group Sites or Social Network Sites. There are usually dedicated sites for different groups depending on what they are doing. Social Networks are much broader, but groups within them like scrapmoms, scrapsisters, and so many more usually share their ideas and projects. It is up to you whether you will join any group if you want to get more details and interact with the people within the group, but you will get templates in there.
Scrapbook Softwares. Whether free or paid scrapbook software, you will definitely get free templates in here. Primarily because these softwares are created for saving your time and effort from all the thinking and researching, so they offer free templates when you acquire them. The next time you try to look for free scrapbook templates, try searching for the above mentioned sites that I suggested. You do need to be more specific in other searches such as the group, theme, and photo sharing sites to narrow your search. Since there are so many scrappers out there, it will not be hard for you to find one that will satisfy your need.