Not many memorable players pre 1970s... only 2 I can really recall off the top of my head. Now just so you know, I am only 40, so I grew up on the 70s Steelers. As far as anyone pre 1970 goes, I would have to say Byron "Whizzer" White and Ernie Stautner. As far as my top 10 list goes in no particular order...
Mean Joe Greene
A Bit outside the box, but what the hell.
I like this list, cause ya got Dirt on it!
Also msdmnr's list!
I'll have to think about mine...