Is there a simple CMS that could manage multiple niche sites on different domains? Sites are very simple and don't need the functionality of for instance wordpress.
I'm currently developing a CMS that can manage multiple sites in the same server. You can use this CMS if you can point the domains you have to the same server. Since you said the sites are very simple you shouldn't have any problem of doing so.
This project was started last year with a web designer. Here is the project link: http://odcms.net/ I just launch a free service for creating personal websites: http://mysite.odcms.net/ Each site can be accessed by either using command link or direct link; for example: command: http://mysite.odcms.net/index.php?usite=_ztml direct: http://mysite.odcms.net/_ztml/index.php You can also use odCMS to generate HTML files for the site. Once the files are generated, you can access the content without odCMS; for example: http://mysite.odcms.net/_ztml/ If you have a domain name and wish to use it for the site's name you can add that into the database. Once added, you can access the site by using just the domain name; for example: http://ztml.info/