Thanks, this was definitely really good feedback. I am going to mull over on where to go with this. I do agree some sort of user engagement is necessary, being 100% anonymous is not interesting.
If you track voting history then you could show quotes that have been upvoted by people that have similar voting history. The actual algorithm probably will end up being rather complex, especially if you want to avoid too strong segmentation. Basically you want to show the users a mix of fresh quotes, "aligned" quotes, and "random" popular quotes.