Eric Christopherson wrote:

> I just discovered Amxrikai Spek in Okrent's book. She doesn't say much 
> about it, but I found a few web pages, e.g. 
> <>. The language uses <x> as a 
> vowel, along with <c>, <q>, *capital* <A>, Greek alpha, and <o> with a 
> mark through it.

I remember coming across that language a long time ago on the net. 
I'd forgotten about it's unqiue orthography.

> For some reason I'm fascinated with the idea of <x> for /T/, but I don't 
> think I would actually use it for that in a conlang. I think I saw a 
> natlang use it, but I don't remember which one it was.

Unless ASCII compatibility is an issue I favor <þ>.  I can't recall 
seeing any natlang using <x> for /θ/.