I recently found a site containing most of the property records for Alaska. This includes mine claims from back to the 1800s, all the way up to modern subdivisions. It's been great for locating unknown mines and ruins, although the locations are hard to decipher (quadrant bearings and distances based on distant and sometimes inaccurate 1900s benchmarks).
http://landrecords.info/ If your state or province has such a system, or even lets you visit their property archives and browse, it's well worth looking into. I pinpointed two small rumored mines about a mile from my house, and another tunnel that I'd never heard of nearby. To get the coordinates I ended up locating and confirming the benchmark coordinates with my GPS, then converting the quadrant bearings into degree bearings and using this tool to get an endpoint coordinate set:
http://www.fcc.gov...bickel/sprong.html, then tracking down the sites with a handheld gps and a lot of bushwhacking and dead reckoning.
I'm planning to do a writeup on the project eventually, but I'm pretty swamped right now with moving and stuff. My only complaint is that they didn't believe in topo maps back in 1905, and didn't think it was important to show that 500ft of a 600ft wide mine claim was up the side of a cliff...