One of my favorites: https://fultonhistory.com/ (click on the "Go and Search My Archive" link). Tom has done an amazing job of scanning and posting old historical photos and newspaper archives, but will it last once he's no longer able to maintain it?
I often hear suggestions like "let Ancestry take them over" or "the Internet Archive is the solution." I have to ask: Will either be operational in 20 years, or the data on them as easily accessible as they are now?
Ancestry is currently operated by Blackstone, the third or fourth PE firm to do so in the past 15 years. Blackstone has no qualms with deleting services that no longer meet its needs (https://scottishgenes.blogspot.com/2023/08/ancestry-disconti...) or paywalling records and then jacking up the price every few years (https://www.ancestry.com/corporate/blog/were-increasing-our-...).
IA's web archive is a great resource, but it always seems to be begging for money and its founder's futile campaign against book publishers isn't helping.