I can't find an example online but there used to be a ton of these kinds of sites called "Top Sites".
It's where people put a listing of the top 20 sites on [subject] and you promote it on your site and ask people to vote for your site. The more "clicks" or "votes" your site gets, the faster it moves up the "Top Sites" list. It's just a big chain so everyone is promoting this same link list in an effort to promote their site.
That's one example. It's harder to find these now because people realize they don't work but they used to be everywhere.
I am so skeptical of any company that says "boost your links" or increase your link popularity these days. Most of the time it's some artificial way that doesn't work and the engines ignore them.
I don't put BlogRush in that same category as webrings because BlogRush is a little more responsible with how links are shown (targeting, etc.) Plus BlogRush's PR is 6. Now.... I'll be the first to tell you how PageRank is waaaaay overrated by Webmasters, but I still think there is something to be said for that.
I've been using BlogRush on my blog since November and my Google traffic has only increased. Not saying BlogRush had much to do with that but my point is I don't think it's hurting either.
Because often times, the only people clicking on those links are the Webmasters themselves, not the actual site visitors. (At least that's what I found in my niche)
Link Farms
So my answer would be "yes."
Webring
webrings
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