Quick Reply Reloaded is also a good one but the Extensions Manager isn't recognizing the current version for some reason. I haven't figured out why.
And a WYSIWYG editor would be great if anyone can recommend one that isn't buggy.
I hard-code ads and Google Analytics but we don't have premium memberships. Otherwise we'd probably use the Ad Management plug-in.
As far as spam, we put new members on moderated posting for their first few posts. No big deal for the mods and it catches 99% of them.
My latest creation, a very long time waiting for an unofficial extension REST of phpBB allowing to connect to phpBB site and a great one.
Oh, goodness of texas hold'em, hopefully there will be interests as it could boost community