Hi,
Is it possible to get the most populair posts from a specific Rainlab.blog category?
If yes, how should I do this?

As far as i know you will encounter the problem that the blog plugin does not save the hits / views per blog entry. I think i saw some plugin in the marketplace, but can not confirm this. An other slution would be that you create a plugin table registering the post ID and hits.

Whenever someone opens that post entry, you make a onStart function within the PHP section that updates said plugin with +1