I've been impressed with this all my life, but after some recent demonstrations like
Majora's Mask Fan Video - Gorgeous!
http://www.youtube.com/watch?v=cyazYYev7Nw
Kirby - epic montage. Look at that sprite work!
full size - http://www.otakufreaks.com/wp-content/uploads/2010/05/Kirby-rules.png
Kirby as Magus from Chrono Trigger is the most badass thing I've seen.
The Mario Brothers - Brilliant. Just brilliant. To get all Nintendo references here you got to be at least lvl 86.
Episode 1 - http://www.youtube.com/watch?v=Kk9oa_PiXAk&feature=relmfu
Episode 2 - http://www.youtube.com/watch?v=tw7CKnfk4JY
Plus infinite other examples
But what really made me do this thread was this... what can be more a symbol of Nintendo love than a man doing his own home made Missingno plushie...
http://gonintendo.com/?mode=viewstory&id=179991
Nintendo fans, we salute you.
Signed: Nintendo Fans