Any service provider offering private newsgroup hosting, for free or for a fee is welcome here. Note that Usenet access providers do have their own category: Computers/Usenet/Feed Services.
Newsgroup hosting services are similar to Web hosting: for those who want to create a private newsgroup to discuss a particular topic, providers listed in this category offer various solutions. Additional services like mailing-list or Web gateways are often available.
However, newsgroup hosting is different from creating a newsgroup on Usenet: groups hosted by service providers listed here are not relayed across Usenet, they're only available on the server of the provider.