Many years ago, the old Auran.com website, the one with the black pages, not to be confused with the black pages DLS, had a list of Trainz content creators. Included in the list were many, many payware creators as well as freeware from all over the world.
I don't think the management is adverse to supporting third-party content creators on or off the DLS because N3V developers do not create content themselves in a quantity to worry about competition.
From the top of my head here's a few I can think of:
A word of warning here. There are some sites, located around the world, that are hosted on less than stellar servers. This is no reflection on the content creators, but on the hosting facilities which are not necessarily clean, have pop-ups and other nasties floating about. My recommendation is to visit these places within a Virtual Machine or using a method that is safer than your general browsing.
Frank_Dean, Thanks for the link. That is an awesome list of sites! John, yours is very helpful also!
And, I would second John's warning, especially on the download links....