Click here for a larger version.
Many sites will only let you put a restricted subset of HTML in profiles etc - so for example you can't use the map above in a flickr profile. Douwe Osinga has a clever approach which can be used in this situation - he manipulates the palette of a gif image on the fly, and so just requires an image to be imbedded which most sites will allow.
create your own visited countries map
or vertaling Duits Nederlands
He has a visited states map for the US too:
create your own visited states map
or check out these Google Hacks.