A beautiful name with an excellent history, but if you're considering naming a girl this, be warned that controversial fantasy author Robert Jordan named a concept in his books after a corruption of the name. See http://en.wikipedia.org/wiki/Tel'aran'rhiod.
I absolutely love this name. "Arianrhod" is a very cute name, and it has a meaning that you really wouldn't think it has. And besides, it's cool for a Welsh name. I'm naming my kid this someday.
I think this actually was meant to spell the name of the moon goddess mentioned for the name of 'Aranrhod' because of the fact that Arianrhod would end up meaning 'silver wheel', which the moon technically could be thought as. I could be wrong, though.
https://en.wiktionary.org/wiki/Arianrhod [noted -ed]