Ritual within Gaelic Polytheism is a solid introduction and overview of the earth-based ceremonies and customs that survive in Ireland and Scotland (and the diaspora). Some of the surviving traditions were lightly Christianised, others not so much. They've kept this work very traditional, and have been excellent about noting when a practice has undergone reconstruction, or when presenting ideas for reconstructing a more elaborate version of a surviving practice. I think they've successfully walked that line we all try to balance in GP, that of giving people enough ideas to be able to pray and observe the customs on their own, without publishing anything too private or personal about ceremony.
In (De)constructing Reconstructionist Ritual, Annie looks deeper into the common themes present in Gaelic rites, and discusses the process of maintaining tradition as well as looking to the ancient Celtic practices for additional material.
Due to it being a basic, consensus introduction, and needing to cover a wide variety of subject matter, we were only able to touch briefly upon specific rituals in the CR FAQ. Much work has been done in the past four years, and these articles are a welcome addition to the field. 'S math sin!