View source for Extensions / Components / Actions

Hello Wacko Team
I'm getting about 42 hits.
I'm getting about 56 hits.

What is the best place to find commercial / open source Extensions / Components ?
Do we have a gallery or market place with additional stuff?

I can see that extension Bad Behavior was pre-installed.
What other extensions are known to be useful?

In Europe, people could require an extension that is dealing with GDPR Data Protection / Cookie Policy Settings.
My impression was, that admin.php?mode=config_security - does not cater for EU GDPR yet.