gia (Level 13)

This question of the "day" was inspired by Janaiblog on Twitter, who declared the first ED for Saki-- Netsuretsu Kangei Wonderland --is the best ending ever. I like the ending there, especially the animation, but it's definitely not my ultimate favorite!
    
I'm a big fan of the Maria Holic ending, which has a fantastic song and really cute retro-game graphics.
     
And speaking of Shaft, they did a great ending for Sayonara Zetsubou Sensei, too.
     
 For all that it got a little TOO popular, I still think Hare Hare Yukai is a brilliant ending.
    
And anyone who doesn't love Cowboy Bebop's ending, The Real Folk Blues, can die in a fire.
 
 
...To name but a few!