Hi there,
I just started with HA and wanted to share my RuuviTag component.
At this point its kind of a mess but I get my measurements out of it and wanted to share it.
I will improve it and keep it updated over the time.
It is made with the https://github.com/ttu/ruuvitag-sensor library. And as template I just took the " Xiaomi BLE Temperature and Humidity" sensor.
Any chance we could some day see RuuviTag as “built-in” component for us casual HassOS users? 
Sorry to hijack this topic. Support for Ruuvitag sensors is added in BLE monitor 3.3.2-beta, but I’m looking for someone to test.
Especially the motion sensor needs some confirmation if it is working as expected. So, if someone wants to help with some testing, please post your findings in this issue. Thanks!