I also have some Free Negro Registers and am willing to do lookups in my spare time (hahahaha) - let's just say "as time permits" :

District of Columbia Free Negro Registers (2 vol) 1821-1861, by Dorothy Provine

African Americans in Anne Arundel County and Baltimore MD (on CD), by Ralph Clayton - this includes 3 books: 1) Free Blacks of Anne Arundel County MD, 1850; 2) Black Baltimore, 1820-1870; and 3) Slavery, Slaveholding and the Free Black Population of Antebellum Baltimore

Register of Free Blacks and also of Dower Slaves, Brunswick County VA, 1803-1850, by Frances Holloway Wynn

and my book: Pittsylvania County VA Register of Free Negroes, and Related Documentation (1807-1865)

* I do have some others, but let's just see how these work out for the time being... perhaps another researcher will also have some of them and will offer to do lookups using those ;)

Alva