I've finished my first rough draft of a PGN upload facility. Simply go to
http://www.lrchess.org/postPGN.php and copy your PGN into the text box. After you click the button, it will run a validation on the PGN. Not only does it check for incorrect formatting, it also finds rule violations (trying to castle after moving the king, moving the black bishop to a white square, etc.). If the PGN passes validation, it will automagically appear in the games viewer.
Please try it out. This is my first release so I'm sure there are a million bugs. If you find them, I will fix them.
It doesn't handle comments and variations right now. That's a huge problem and one that I didn't even realize existed until I tried to play with it. I'll have another release of it that will take care of those issues.