Someone recently posted a link to a very useful map showing the boundaries of the OW "continents" as defined for an xONEx. I've tried to find the post, but without success. Here's the link: http://www.oneworld.com/content/library/c2852-4_poster.pdf.

I think the map dates from April 1st, 2007, so there could be some minor updates. There certainly appear to be some anomalies: e.g. The Galapagos Islands off Ecuador are shown as part of N. America, which I rather doubt. Nevertheless, it could prove useful as a tool when planning.

Edited to add: Tracked it down - Thanks, serfty, for this