We have a friend who is a geologist so every one of his sheep is named after a rock - they get more and more obscure each year
I have done the flowers thing, herbs, rivers, place names in Shetland, place names in UK, place names all over the world, old battle ships (some good ones there), steam locomotives, famous women in history, characters in books (I think our reg sec likes to identify which book I've been reading
), specialist spinning words, types of antelope (my favourite was Kudu), heavens, the list is endless. I have the advantage though that I don't do the alphabet thing, just the theme. Sometimes buyers want to choose the names themselves which would disrupt an alphabetic sequence. Sometimes my tups have different types of names to the ewes, in fact they usually seem to name themselves. If they are of a good line then I usually carry the name on eg Tam has had offspring called Tam Lynn, Tam's Brig, Wee Tam, Tam O'shanter, Jock Tamson's Bairn - you get the picture. Sometimes I do it with ewes so Bracken had a daughter Fern, Jezebel had a daughter Scarlett, Freia had Freda, Freya, Freyalyn, Annie had Annette, Anita, Anwen, etc.
There's still pop groups, marques of car, trees, stars and constellations, oh many more.
OK I'll shut up
Now I wonder what names I'll choose for this year