In the cases of "BLINK OF AN EYE" and "DEMON", I wouldn't call those deliberate violations. In the former, they were trapped in the unusual gravity of that world. In the latter, the silver blood was not even shown as existing until most of the episode was done.
Some Prime Directive violations...
Arguably, her actions in "CARETAKER" are a Prime Directive violation, as she destroyed the array because the self destruct was damaged in the battle. But if the battle never happened, the Caretaker's self destruct would have worked and the array would have been destroyed, so same result.
Warping through the territory without permission, and after being warned, in "THE SWARM" would constitute a violation. Maybe not of the Prime Directive, but certainly any number of Starfleet regulstions, as Tuvok pointed out.
Getting involved in the Species 8472 war with the Borg... Prime Directive violation in the worst way, because it allowed the Borg to continue to kill and assimilate billions across thousands of worlds.
Giving the Hirogen hologram technology. That's a societal change on a fundamental level, for good or bad. We clearly saw some bad results years later. (Rather unbelievably so, since that's about 35,000 light years away.)
Letting the Vaadwaur loose.
I'm sure there are at least a couple others, but that's off the top of my head.
