TheGenalogist is indexing all the PCC (Prerogative Court of Canterbury) wills plus plenty of others they have collected. They have so far indexed and photographed about 800,000 PCC wills which is about 75% of the total. They seem to be adding quite a few each month.
Prior to 1858 your are almost certaint to find a will, if it exists for a given person, in the PCC collection.
TheGenealogist also has Bristol, Edinburgh, some Irish, Leicestershire, Northampton and Yorkshire indexes of Wills.
You can also search for the PCC wills (Indexing provided by TheGenealogist) at the national Archives here...
http://www.nationalarchives.gov.uk/documentsonline/wills.aspYou will need to use ARCHON to find the depositories of other wills.
http://www.nationalarchives.gov.uk/archon/Some wills and many probate notices an be found in the Churchwarden Books, Bishops Transcripts and Parish Chests.
If you search the National Archives (or local archives pointed to by ARCHON) for a name, you often find wills and probates amongst bundles of documents kept as "sets".
For instance, I found a heap of Dodd ones in the Shropshire Archives.
Probably the easiest way is to use the Access To Archives search facility.
http://www.nationalarchives.gov.uk/a2a/advanced-search.aspx?searchType=aAustralian Wills are slowly being fully indexed and placed online.
Very soon all the Victorian wills up to 1992 will be online.
Currently those up to 1925 can be found here.
http://proarchives.imagineering.com.au/index_search.asp?searchid=54