One of the newest parodies that emerged to popularity is the DRRR!! anime's ending theme, being recreated for another series.
And these are awesome, so awesome.
If you don't have time to check all of the videos linked, check the ones with a red star * mark, these are the best of the best in my humble opinion, the top three of my choice are at the end of this post, so scroll down if you only want to see these :)
One of the reasons that it spread like wild fire is it's ease of being recreated, if you are a good artist, just draw the characters that you want with similar positions and have the picture scroll down with the music playing, add some touches at the beginning and the end, all of this with basic flash knowledge.
But here is the ones that impress me the most, a combination of factors i chose for theme to be in the post, 1) the art my be great of course and 2) the scrolling is smooth. 3)the series' here are from franchises that i actually know :P
since most of the videos are from niconico, a Japanese equivalent of youtube, you'll need to be registered there to watch the videos, here is a guide to do so.
http://www.youtube.com/watch?v=NFMYghNSj3Q All the series' main characters.
http://www.nicovideo.jp/watch/sm9912852 *FF VII *
http://www.nicovideo.jp/watch/sm10403534 Dissidia, although the scrolling is bad and the characters just float there without interaction between them (the art is fantastic though).
http://www.nicovideo.jp/watch/sm9977272 a better Dissidia, the same scrolling problem, but it is a proper one this time!
http://www.youtube.com/watch?v=JGhmyuDGcDU *All of Cloud's appearances in videogames *
Tales of Graces
http://www.nicovideo.jp/watch/sm10892688 ***The whole series's main characters with some GYM leaders, the addition of the new Black/White main characters makes it the best one yet!\o/ *
http://www.youtube.com/watch?v=XbGuEpTp10g The whole Manga series's heroes
http://www.youtube.com/watch?v=5lQ7Kf7_i68 Gold/Silver/Crystal/HeartGold/SoulSilver (in short, 2nd generation)
http://www.nicovideo.jp/watch/sm9536834 Diglett (ROFL)
http://www.youtube.com/watch?v=TzKdIGPHEZA Phoenix Wright
http://www.youtube.com/watch?v=zICyoeMI9B4 Apollo Justice
Harry Potter (?!)
The World Ends With You
http://www.youtube.com/watch?v=FAqcB6ggpUU *****one of the best games ever to get one of the best DRRR!! parodies, this is the 3rd best one here in this post!
http://www.nicovideo.jp/watch/sm10888207***** This is the second best, it is drawn with black and white manga style and the interaction between the characters is pretty unique and awesomely drawn.
Axis Powers Hetaila
http://www.nicovideo.jp/watch/sm10580327 ***** I don't even watch the series, but this is the best DRRR!! parody i have seen, this is by far my no.1 pick, not only the art is great, but the song is uniquely remixed, and the iteration with the characters are awesome.