Some parts, mostly RF, are arranged 'backwards', with E/S on the case and B/G and C/D on leads. I understand some of these are actually done with the substrate being E/S, though I'm not real clear on how.
All power packages, that I'm aware of, have the center pin not only connected to the tab/case, but made as a part of it (from the same stamping or whatever). This is awkward for some components (e.g., TO-263-5 case gate drivers; the IXDD614CI for example has the 'selling point' of being grounded case, unlike others, IIRC).
"EBC" TO-92s I guess were common enough that they went to the trouble to make a suitable leadframe: if you've ever cracked one open, you should see a coined blob on the side (collector) terminal -- just like a power device, except the back plate is fully encapsulated. (There's also a TO-92 variant with the tab brought out, TO-237. See also the TO-202, which is like a TO-220 with a similarly flimsy tab.)
Tim