I just finished another large round of scanning. They haven't made it to Brickset yet as far as I know (the previous scans have thankfully already been posted there.)
TL/DR look at old catalogs here:
https://archive.org/details/@eamonnmr?and[]=lego&sort=-publicdate
The web view is kinda slow because the scans are really large, but I've bundled each one into its own much smaller PDF. The first wave had slightly wonkier PDFs but I've got a process nailed down for making them now, so if anyone wants me to go back and re-upload smaller PDFs I guess I can do that. The older ones have been added to brickset (so you may have already seen them) but the latest batch hasn't been yet as far as I know.
Why do this crazy thing?
Back in the day I spent many hours reading through the lego catalog. I think things like this should be preserved and shared. I also had older catalogs when I was a kid that wore out and fell apart; I was curious about what year I'd seen the Unitron Monorail, for example. Anyway, once I got started I got very well carried away, and I figured I might as well finish what I started. My hope is that if if anyone is as nostalgic as I am for this sort of thing, they enjoy it as much as I did.
What did you learn?
It's a really interesting way to take in the story of Lego's 20th century themes, how they evolved into a more narrative and tie-in based setup in the late 90s, and licensed themes/Bionicle and Juniorization in the early 00s. Beyond the nostalgia, it's interesting to see the marketing material evolve over time, especially the most cutting-edge stuff which culminates in Bionicle's CGI world. Also what I assume is the better and better technology enabling editors to reuse more and more entire pages (which does make the late 90s/early 00s catalogs get pretty samey.)
What are your favorites?
These are obviously subjective picks because i was a kid dammit but here they are:
1997 Holiday: Carried this one around till the binding fell apart, and kept the Space Monorail and Starhawk II my memory for a while besides: https://archive.org/details/1997HolidayUSLegoShopAtHome
1999 Summer: Rock Raiders featured in a transition period between being all-in on house themes and all in on Star Wars. Oh and it has the last appearance of a bunch of really cool sets: https://archive.org/details/Lego-Shop-At-Home-Summer-1999-Rock-Raiders-Cover/mode/2up
2001 Summer: The introduction of Bionicle: https://archive.org/details/Lego-Shop-At-Home-summer-2001-Bionicle-Cover