[dmckeon]

In the USA, 10-year census records since 1790 and immigration records are great resources. The LDS church has done a lot of work microfilming many church and government records that remain available, and has had volunteers transcribing and indexing them. For the British Isles, property records are a good resource - if the people being researched owned or bequeathed property. Research-sharing sites such as ancestry.com can help connect Nth cousins who may be looking for the same remote ancestors.