I'm always surprised at the love TINAD gets, when I never hear "Ra" mentioned. From the same author, in my opinion a better story, doesn't rely on the whole SCP thing (which I never got into).
TINAD didn't stick with me at all beyond the time I spent reading it, whereas Ra did in a way.
Oh man, Ra was fantastic. I love when you learn why magic was discovered in the year it was. It took me ages to correlate the two seemingly completely separate stories going on.
Ra is great, and so is Fine Structure but they are both significantly longer than Antimemetics. Most people wouldn't read a massive novel publishing on some guy's personal website.
TINAD didn't stick with me at all beyond the time I spent reading it, whereas Ra did in a way.