Invidious lets you browse and watch YouTube videos without actually using YouTube directly - giving you some privacy from the all-seeing Google. For best results, combine with a good VPN.
No account necessary to use, but you can register right on the page to save preferences and history.
I already mentioned the Gitea instance on the social platforms page, but I'm never sure which it is. I decided that it is collaborative, and therefore social... Ultimately, though, I want people to be able to find it, so it's here too!
Point is - there's a Gitea instance, which lets you host your git repositories in a nice, safe and non-corporate place. For the features and such, do checkout the social platforms page - or just go ahead and make an account. (I'm aware the captcha isn't accessible - I'm working on that, but for now, if it's a problem, you can get your account setup for you).
The Lounge is a web-based IRC client. Login, join your server & channels. It'll keep you connected (and preserve your scrollback!), and you can login from any browser to chat. There's no direct registration, so you'll need to request an account.
RSS Reader, Nitter, and more
Coming soon - look out for it on Mastodon.