I've mentioned before that, once probate is granted, a will is a public document.
This makes them quite interesting for historical purposes. Not only do they help fill in details about family trees, they can give more interesting details - mentioning friends or interests the person might have had.
Amateur genealogy has become more popular in recent years because it can throw up some interesting details about the past that are ignored by the black and white characters in many 'period dramas'. I came across this Sussex genealogy blog this week and a page on how probate records have been used to help.
If you're not sure what probate is, see our explanation page.