Almost as soon as I'd created this section suggested by Jaqhama, it occurred to me that people would be wanting it divided into paying or non-paying sections. Maybe I'm wrong. Anyway, it seems it would be simpler to just post links to the various markets, and people could find out from their sites whether they pay or not. Some small-press markets are nonetheless paying markets.
I would suggest that new threads are started here for each market, otherwise we'll probably end up scrolling down one miles-long thread.