If your like me and use a lot of videos from youtube you may have noticed that they track the top referrers for any video and place the top 5 referrers below the said video, the section is just above the Comments & Responses and only appears if people are linking to the video. I have found a lot of sites in my various niches that I hadn't known about before using this feature from youtube.
What it shows is the top 5 links that are linking to the video along with the amount of traffic that each link has sent.
You can use this information to find out who some of your bigger competitors are as well finding sites that may be similar to your own that you could possibly trade links with, network and communicate with.
I usually only post videos from youtube that are new, maybe a week since the video was uploaded and I find this feature useful to get a real time picture of who else is writing or updating about what I may be writing about at the same time. Since the amount of traffic is tracked I can see how good I am doing compared to my competitors.
I am seeing a little extra traffic from getting onto the top referrers lists also, especially if a big site links to the same video that I have and the video gets popular, I may get pushed down on the referrers list but most of the time I'll stay there. For example for this video I was the top referrer for awhile, sending in about 5000 hits, then a bigger site linked to it and sent about 22,000, which pushed me down to second spot, but I'm ok with that.
Even if you don't use youtube videos I think you could use this feature to look for videos that are similar to your own topics and find new sites that are actively updating (if you search by date) and how much traffic they are generating.