The following is NOT intended to provide legal advice to anybody, just to quote some relevant material.:
To be protected by copyright, a work must contain at least a certain minimum amount of authorship in the form of original literary, musical, pictorial, or graphic expression. Names, titles, and other short phrases do not meet these requirements. U.S. Copyright Office Circular 34 (.pdf)
By presenting facts drawn from your site, I am not drawing visitors away from your site, since no self-respecting researcher would rely on information on this site, but would need to verify it, and the first step toward such verification involves visiting your site.
If your material is on HTML pages, you can modify them to call attention to the other cool stuff on your site.
The material, where possible, has also been compiled into GEDCOM files at http://gedcomlibrary.com/vitals.html. These are readable by any genealogy software and a variety of utilities. You can copy these onto your site. (What am I gonna do about it, sue you?)
The conversion of material into GEDCOM files will facilitate the compilation of indices. While GEDCOM may not be the most efficient way to store genealogy data, that only means more work for the computer, not for the humans (except the programmers. 8-( )