I just had a thought about the Keldas... I've only read The Wee Free Men so far from the Tiffany Aching series. It was mentioned that a Kelda must take a husband and make lots of little Nac Mac Feegle. Tiffany was smart enough to figure her way around this, at least for a long time. It was also hinted that the queen tricked the clan or a clan or possibly all clans into becoming their Kelda.
Has it ever been explained how/if the queen got around this? Though the thought of lots of elf/pictsies running around the place drunken but elegant is pretty funny.
-The elfs remind me of another favourite quote: "Are you Elvish?"