This is more about my wife's ancestors than my own. My wife was a Jones (oh no!, not one of those I hear you say). She is now a Hughes, can it get any worse for looking up Welsh ancestors. Erm actually it can because she is descended from a very long line of Williams.
In order to do the research for my wife I've acquired the complete census returns for Caernarvonshire (now Gwynedd) in North Wales for the years 1891, 1881, 1861, 1851, and 1841 as well as a lot of other bits and pieces too numerous to mention in this post. If anyone wants a look-up then just ask
My wife's ancestors are all from the Lleyn Peninsula in North Wales (it's the bit that sticks out and looks as if it is pointing to Ireland) Two of the better websites for this area are RHIW