I can only speak to TBs. When I say it’s independent of performance, I mean that they are able to pass on performance for generations through daughters. But in Germany, there is the line of mares who descend from Waldrun. In the UK and US, there is the Uvira line, the Black Ray line, the Dynamo line, the Imperatrice line, the Cherokee Rose line, the Padua line, the Aloe line, the Agnes lines, the Pretty Polly line, the Lady Josephine line, La Troienne and Adargatis, the Goody Two Shoes line, Queeny, the Bonfire line, the Beaver Street line and so on. There are actually quite a few of these. These are lines that with much regularity are able to pass on quality for sport and racing to the foals.
In history, there are Queen Mary and Pocahontas, Concertina and Black Duchess, and the greatest of all for sport, The Alexander Mare of 1790 and her daughters.
I’d agree that poking around in TB Heritage is very educational, but would add that poking around here is also worth the time:
http://www.bloodlines.net/TB/Families/FamilyNumbers.htm