This is one of my favourite time-wasters - finding my roots, and researching where and how they lived. Consider this page a summary of 'knowledge depositaries' sprinkled through the web.
Ancestry (UK)
A fantastic site, with some free resources too. They also have a ".com" and ".co.au" section too. Membership is particularly recommended as it gives you access to a vast collection of records, perpetually improving search functions, and a family tree building programme.
Family Search
The IGI (International Genealogy Index) is only one part of this excellent (and free) resource. Not all parish records are available, but it's a work in progress (as all ancestry records must be).
New Zealand BMD records
Links to original records for New Zealand births, marriages, and deaths. Information available depends on the year (i.e: "births that occurred at least 100 years ago"), but for the information there it gives references for ordering original certificates.
