I don't remember any, but then again, I don't know when I (or most people) would have come across them if such a thing existed. If you wanted Napster, you just went to napster.com and downloaded it. There wasn't a gameable walled-garden app store like you have to go through to get uBlock Origin.

There were (and still are) sites hawking anything popular - games, porn, desktop apps, etc. If someone was lucky, they ended up with a bunch of adware slowing their computer down. Worse scenarios involved things like programs which would surreptitiously hang up your dialup connection and redial the equivalent of a 900 number in some country where the scammer could pay off the local police.

Search for something like "flash update" on non-Google/DDG search engines and look at the top ads if you want the general feel.

I don't think stuff like that became popular until BitTorrent and other distributed filesharing protocols and clients came about. Lots of people were tricked into installing malware while trying to download warez and porn, though.