This is a handy tool developed by Ben Buckner to help calculate birth dates from the death date and age at the time of death. Many old tombstones and death records list only these two facts and leave it to us to figure out the birth date.
http://www.searchforancestors.com/utility/birthday.html
Below is a list of sites that they use when conducting Canadian genealogy research. These are all searchable online databases or informative tools.
"ProGenealogists" are a group of professional genealogists who specialize in genealogical, forensic, and family history research. This group was involved in some of the episodes of the "Who Do You Think You Are?" series on NBC. When you need help on just about any genealogy topic try using: http://www.progenealogists.com/articles.htm It has a wonderful collection of well written articles and research tools. The links below are the bookmarked pages they use when they do their research. Their list of the best U.S. genealogy databases is: http://www.progenealogists.com/genealogysleuthb.htm Their list of the best International web sites is: http://www.progenealogists.com/genealogysleuthi.htm They also have other "sleuths" for Ireland, Canada and Great Britain at: http://www.progenealogists.com/ireland/irishsleuth.htm http://www.progenealogists.com/canada/sleuth.htm http://www.progenealogists.com/greatbritain/britainsleuth.htm These are great pages - refer back to them often. It's certainly my "go-to" reference source.