Free People of Color Population in the US: 1790 – 1860, a demographics chart created by Erin Bradford of Free Blacks in Antebellum North Carolina. An interesting comparison of Free POC populations in the Northern states versus in the Southern (later Confederate) states.
Look out world – here comes the iceberg! from Tami Glatz at Relatively Curious About Genealogy (I just love that name). This post gives a brief look at digitization projects and the availability of online records. Poke around, as Tami has written a couple of other good posts.