Check out the "Leadpages Community", "Automation Nation", and also the "IFTTT and Zapier for Online Sellers" groups. For ActiveCampaign users, check out "ActiveCampaign (Official)" and "Activecampaign Juggernauts User Group"
The Zapier group is sleepy, mostly because I think people don't know it exists. It was called something else until recently, so it didn't show up when people searched "Zapier".
There's a lot of good info in these groups!