I've created bskytoolbox.com It's a fun little project that uses blueskys amazing websocket firehose to make some cool little tools with it.
Most of them just connect to the firehose using JS so nothing is stored server side but the one I like the most is the mentions tracker. This connects on the backend with a simple python daemon that tracks for words you ask it to. It's pretty cool and a good way to see things you are interested in on bluesky.
The code is here if you are interested: https://github.com/oidz1234/bskytoolbox