I manually sync it, because I have 2 computers. That's why I can't use iTunes' get artwork option to automatically retrieve artwork for songs on my iPod.
Even if it updates artworks on my computer it doesn't copy them to the iPod when I connect it, as it's isn't set to autosync the music.
I hope that makes sense.
EDIT: Forget about this post, BoyBach, you rule! I selected my iPod and tried your method, it works! Thx a ton!
EDIT 2: Doh, turns out that it doesn't really work... 🙁