Thanks for the info: I was taking Ben's idea and saving it in OO and then using Calibre to format it.
I have written my novella (8,000 words) called "Invisible" and just editing it.
I'm rather taken with this Kindle Singles idea, hence the need to pick up formatting asap.
I was intrigued by you saying you save in word-filtered HTML. Do you know how I would do that in OO if I wanted to go your route and use Mobi?