I've written a website that archives all my posts/tweets/toots/skeets across different microblogging platforms!
It's fun to be able to see similar posts that I wrote at completely different times. It also lets me edit links that have bitrotted.
Trying to import an interesting old CVS project into git. Even the import tools have bitrotted!
git-cvsimport relies on cvsps before 3.10, which came out in 2013.
Playing with LambdaMOO is an amazing time capsule into computing history. It really needs a good client (i.e. not just telnet in bash) but many clients have bitrotted severely.
I ended up using a basic Emacs client: