I ask because if there isn't one already, I'd like to release ayttm's tcp library as a separate project that would be of use to others.

Let us know if you find good ones

I would also like to look at a separate library that does asynchronous dns lookups.

adns. By the same guy who has written "putty" for win32. http://www.chiark.greenend.org.uk/~ian/adns/

--\ cheers