LinkedIn specific industry groups provide insights, but some groups aren't too active.

I typically use 3 techniques to stay current.

• Twitter scavenger hunt - I review tweets from segmented lists of leaders on a given topic or industry. I look through trending hashtags to see if anything warrants my attention. I check industry hashtags (even if they aren't trending) to see current level of activity or discussion.
• Review related blogs and websites - I check industry related blogs to see if there are any new posts for the day (and then to see if they are of interest - I won't just read every new thing). Then I move on to websites that are known for surfacing emerging ideas, products and services (such as Product Hunt).
• Local Events and Meetups - I try to go to local industry meetups at least once every other week to hear what other locals in my industry are seeing or watching.

I do also use LinkedIn groups, but as Steven said, I find most to have limited impact for me personally. Many are not very active or the ones that are don't seem to bring up topics that personally interest me.

I use LinkedIn also. You can check what groups people are following in specific roles and industries. I also subscribe to media alerts and specific industry publications. As an example, in the HR field it is AHRI, and HC Online. If the industry is construction for example, I would use media alerts, regulatory bodies' websites, and Tendering alerts.

There is Seek where you can see what is going on too, industry whitepapers and good old google. Try googling "industry trends" - Deloitte have research stats as does business government websites.

I hope this helps.