I havn't done many custom sprites. Most of the ones for RO that i have done were colouring RO sprites.
This is the first one I did:
(http://img.photobucket.com/albums/v462/PerfectDeath/DarkKelGoraRO.jpg)
A sort of evil swordsmen with a big sword =D
The next one I did was just re-colouring a ninja sprite to make it look cooler:
(http://img.photobucket.com/albums/v462/PerfectDeath/Ninja_Ken.jpg)
I've never actually one a full sprite set for any RO characters =\
But I have done my own sprites for someone who was making a naruto game: (http://img.photobucket.com/albums/v462/PerfectDeath/GreyFront.gif)
This just shows one of the walking animations I did. I've done about 5 full walking sprite animations like this.
I learned from this experience that spriting takes a LONG time =P
My other spriting experience comes from making some sprite comics. Now they wern't great, but I did them mostly as a learning experience for when I get around to making graphic novels.
You can find my GM parodies on my photobucket link: http://smg.photobucket.com/albums/v462/PerfectDeath/Comics/
I did these while i was GMing for a server. They might not be all that funny if you wern't actually there =P
I'll also throw up my deviant art gallery which has my first attempt at doing a sprite comic. Also you can find some of my non-sprite comic works. http://chizek.deviantart.com/gallery/
Thanks for checking out my work, if you did =P