Tor, so far as I'm aware, that American Forests is the main registry. You may also enjoy reading the many tales to be found at the forum of the Eastern Native Tree Society website. Despite the name "eastern"....these folks are world-wide in their explorations. If you really want to dig in with the true tree measurement experts-guys that will actually go to Borneo or somewhere to climb a new record Shorea or something.....that's the group. I'm an outlier there-I have the basic tree knowledge but don't have the skills or knowledge that these folks have. This is the real deal.

Wow. A couple 150' ft oaks. Those will be targets for lightning. I did see a forest grown black oak that I thought was near 150' on the grounds of a tourist station along the Blue Ridge parkway near Ashville, NC.

Speaking of sizes, what's the best way for a novice to measure tree height? I would love to be able to reasonably estimate some of the trees in my woods, as well as the monstrous old Swamp white oak on the neighbor's property line. Opinions?

You can use a tape and a pencil or stick if you look up and learn the method. And don't have fancier gear like a laser.

I post full sizes of tree species to show that they are too much for small planting sites, based on their genetics. Many want to plant forest giants or other large growers where there is room for a small (15-35 ft.) tree - if that. The fact that there is one 150 ft. tall somewhere shows that even if their planting were to reach only half that size it would still become out of scale with the site. Otherwise it should be kept in mind that a dominant pattern is for there to be many thousands of much smaller mature examples living on more ordinary sites for every one that happened to land in a sheltered ravine with moist fertile soil or other prime location that made champion size achievement and longevity possible.

from the alabama forestry commission's website, see alabama champion trees

from a quick look, i see the tallest are a 146' tall shumard oak and a 153' tall yellow poplar. national champs include myrle oak, scentless bayberry, alabama black cherry, southern shagbark hickory, durand oak and co-nationals of laurel oak and sparkleberry.

Maryland big trees:

http://www.mdbigtrees.com/view_tree.aspx

Some good links there. Perhaps an enterprising fellow with a website will combine the data....

Any links which show average range for a state? like if you plant a redbud in Missouri expect this tall by this wide?

Again, that group i mentioned...I should call them by their proper name-Native Tree Society-has scads of information on just that, indianagardengirl. Seriously, I'm no expert at all, but a lot of the folks there will tell you ten different ways to do it. And get accurate results. These people are serious. For example, lidar estimates of some newly-reported height records for some species in Borneo are considered utterly unreliable by this group. Others, in other walks of life, consider lidar very accurate!