The National Library of Wales in Aberystwyth said the wills dated from the 14th Century until 1858, when civil probate was introduced, and 1,000 of them were written in Welsh.
It said the project was "good news for family historians, social historians…and the inquisitive".
You can read more at the BBC web site at http://news.bbc.co.uk/2/hi/uk_news/wales/mid_/8316533.stm and on the National Library of Wales web site at http://www.llgc.org.uk/index.php?id=1514&no_cache=1&tx_ttnews[tt_news]=2640&tx_ttnews[backPid]=2&cHash=adbaf61688.
The wills are available http://cat.llgc.org.uk/cgi-bin/gw/chameleon?skin=profeb&lng=en.
My thanks to Michael Kinsey for telling me about this resource.