You've jump-started my recalcitrant memory cells.
The carskins that I'm looking for were painted by Camillo Holquin.
Starting in 2003, he painted every single F1 livery from the first race of the season through to the end, with every single minute change for every single race.
I didn't download all of them when they were first uploaded, other than the 2003 ones, and when I went back to download the rest, some time later, almost all the links to them in the old downloads section here were no longer working.
They were uploaded here as either individual carskins or as sets of carskins for individual races.
I would very much like to get ahold of all of Camillo Holquins carskins from 2004 onwards, as well as any other similar sets by anyone else from 2004 onwards.
P.S. Paul Edmonds (aka The Smoking Pen) did individual race carskins for his CART carsets from 2001 through 2005, but his F1 carsets only had single liveries for each team for each entire season.
The only other person that I definitely recall as doing individual race liveries was Ralph Hummerich, from his 2001 set onwards.