Shields on a Galaxy Class require 400 GJs to knock down, plus, in "Yesterday's Enterprise", the Ent-C was referred to as having shields roughly half the strength of the Enterprise 1701-D, which of course, means that it can withstand around 200 before it's shields collapse.
From this, I backteched the shields to get the Excelsior's (160), the Constellation's (140), the Constitution and Enterprise's (125) the Miranda's (100), and the early TOS Pilot Const's (75).
...Plus, there are Types VI-VIII torpedoes that go through the movies, and Mark IXs' in some late TNG-era stuff (I think, probably a 6th season DS9).
...Also, someone actually gave shields type numbers, implying that there were at least four types of deflector shields (this was in Gambit, part I), and the Type 4 was an older, moderately strong generator.
...One more thing, in DS9's "Valiant" episode, someone implies that Warp Drives go up to a Class M, and Simon and Schuster's "Starship Creator" implies something way different; that there are at least 13 numbered types of warp drive, plus a class K and XP.
...More interesting details here will pop up shortly.