I just set up an old white Macbook (early 2008) with a fresh install of OS X 10.7.3, which I think is the most recent version that will run on it. I was surprised to see the installer did not include a version of iPhoto, but I guess in those days the iLife suite was bundled separately, rather than built in to the standard install. As far as I can tell there's no way to download iPhoto (any version!) from Apple. Any suggestions?
...and, I'm answering my own question. Apparently (this comes as a surprise) the entire iLife '11 DVD is available as an ISO from archive.org (https://archive.org/details/iLife_Install_DVD_Version_11_2Z691-6677-A_Apple_2010). I'm not sure whether that's legal or not -- I would expect archive.org to be careful about clearing copyright before hosting uploaded disk images, but maybe not. If this is considered software piracy then please feel free to delete this answer.