Content Syndication - How to find such sites?

I noticed a remarkable jump in my daily traffic largely thanks to two sites that started using my rss feeds to syndicate my content. it's amazing to note that these sites have their own twitter/fb publishing in place, so the traffic is funnel'd from their site and ends up on my site.

Unknowingly at some point I started using ads in my rss feeds and besides the traffic spike I'm also seeing decent conversions (better than previous months).

Is there a way to find such sites? Lots of people have autoblogs here and are there any footprints left behind so it would make it easier to find such sites and contact the webmaster to syndicate the feeds?