I'm just passing on a mini-insight I found out today from Quora. I was wondering how to find the most popular groups on Linked In. The answer is obvious, but I didn't think of it... Simply select "Groups" from the search drop down and then search without any query in the box.
The number of members is given under the listing. It seems there are nearly 900,000 groups on LinkedIn - that's quite a few.
The popularity of some these groups is amazing, many of them are jobs related, which is no surprise, but I was interested to see that the Emarketing Association was the third most popular - this was one of the earliest groups created around our topic:
Finding the most popular LinkedIn groups within a category or industry
This is most relevant if you work in B2B marketing, in which case you've almost certainly done a search like this. Finding out the most popular groups is more obvious, simply enter the industry you're interested and the results are returned in popularity order with the ones shown.
This question may also have more personal relevance, if you work in a niche - find other marketers like you. For our category, the main groups are clear, but other niches like Fashion and Sports marketing are popular too: