I'll start the ball rolling~
Guess this was inevitable.
"Haruhi Live Action ED Parody"
http://www.youtube.com/watch?v=FSpwiGFyvo8
"Haruhi Live Action ED Parody with Comparison"
http://www.youtube.com/watch?v=r8ybjdPSLGI
More of the ice skating dude.
"Haruhi OP [Full Dance edit]"
http://www.youtube.com/watch?v=Yw6cPB6Gcts
A merging of the OP and ED.
"suzumiya haruhi no yuuutsu ED [edited ver]"
http://www.youtube.com/watch?v=3_E3wOq0uuA
Most people should have seen this by now, but here anyways.
"Haruhi ending with gundam parody"
http://www.youtube.com/watch?v=u12gN1s6lik
"The Melancholy of Suzumiya Haruhi w/ Gundam Comparison"
http://www.youtube.com/watch?v=SvoQz4mSHOo
There's also alot of Mikuru Beam edited videos on YouTube, so I'll just post this one.
"I make the impossible... possible!"
http://www.youtube.com/watch?v=qwy6CbOiYes