Use interlibrary loan a lot . . .
My rankings are based on criteria similar to what T&FN uses for their annual World Rankings. Most important is Honors Won (meaning performance at the bigges and most important meets), followed by World Rankings (instead of T&FN's Win-Loss record, with emphasis on ranking #1), and finally Sequence of Marks (which I adapt to mean world records and the like).
The biggest problem that comes up is that world rankings only go back to 1947 (men) and 1956 (women). So I did as much research as possible and came up with a top-three ranking for each year before 1947 and filled out the top ten by the annual world list. Not a great system to be sure, but the best I could come up with. I only did a top-five for years where there was little international competition -- the World Wars, and most years prior to 1912.
I photocopied every annual World Rankings section from T&FN (available at only one library in my state!) and that was a gold mine of information. Certain books, "The Milers" being the best example, profile a certain event or range of events. I went to the National Track & Field Historical Research Library when it was still in Indianapolis and dug p a bunch of things there -- it has since moved to Los Angeles and melded with the Olympic Libary there, so it's beyond my reach now.
Other very useful items have been a series of books that ATFS published, called the "Track & Field Performances Through the Years" series. It's their attempt to reconstruct annual world lists prior to 1950. Volumes I (1929-36) and II (1937-44) are no longer available commercially, but you can still buy volumes III (1945-50) and IV (1921-28) through the IAAF ( http://www.iaaf.org/newsfiles/19764.pdf
). Another publication that is very useful is the IAAF's "Progression of World Records and World Best Performances", which lists detailed information about every official and unofficial WR ever set, in some instances going back to 1860 or so. Ian Buchanan and Bill Mallon put out "U.S. Championships in Track & Field Athletics" through USATF, and their book has complete results of every men's USA track championship up to 1985. Richard Hymans' "US Olympic Trials Track & Field 1908-1992", also published through USATF, has similar info about every OT meet ever held. All of these books have come to me through interlibrary loan, so you should be happy to pay your local taxes since they bring the world to your door!
Online info I've found:
Top ten world lists from 1900 (with some minor inaccuracies) and top-eight results from all Olympic, World, European, and World Cup competitions:
Complete results of every Commonwealth Games:
Medalists from every international championship wou can think of, plus national championship winners from every nation of any significance:
Britain's National Union of Track Statisticians (NUTS) has some booklets and other things you might find useful (try "other publications" and "historical group":
I'm sure you know about some of these things already, but I thought I'd empty the barrells for you.