There are a few genealogy sites that have compiled records.
There are things like
http://books.google.com/books?id=b7GX427EbLAC&pg=PA328&dq=slave+register#PPA328,M1 that have partial records (mostly *not* on Google books). I.e., Gallatin County, Illinois Slave Register, 1815-1839
by Rebecca Schmook, Mss5: 5B6387: 1 or William Bolling Slave Register, 1752-1890, Goochland County, Virginia by William Bolling.
(My father-in-law would have heard, no doubt; he's massively into his family's genealogy, tracking down not just his lineal ancestors but also all the descendants from his ancestors ... when you trace them back to the 1400s, you get lots and lots of names piling up real quick. Anyway, some of his folk owned slaves in Virgina (and elsewhere)--not hugely prominent, they were important in part of Virginia. And here and there I've run into references to a half-white slave or two from Virginia bearing his family name. Since *he* isn't notably racist, he'd also love to track down *their* descendants.)