How are the quotes collected? Are they collated by users or by some algorithm? They seem too good to not have some user input in their filtering?

yes, the quotes are individually approved by moderators, and on bash.org, rejected quotes never see the light of day.

the submissions themselves are also put together individually.

How does one collect funny IRC contents via script?

It's funny that this should come up on the frontpage today, because just yesterday, I chose to go and find and install ircN, which still works just fine, by the way.

That is how I collected the quotes originally, by using ircN's quote commands, which saved them in a file called quotes.txt, IIRC.

Then, I would occasionally entertain the channel with random quotes.

Eventually, I converted quotes.txt to quotes.html and posted it on my website.

Then I built a PHP+MySQL database with a submission form, then some basic anti-abuse and moderation features.

Doesn't really answer the core part of the question - how did you fish out the funny ones?

Manually

Do you still use IRC?

Yes, I still love and use IRC, and I just recently installed mIRC and then ircN, and aside from nostalgic value, it's still great for conversation. irssi is my go-to client in general.