Best way to get album art for my ipod?

whats the best way to get album art for my ipod? any suggestions on a program i could use or is it easier to just get the images myself off of google or somehwhere? also, will i be able to update them to my ipod as well as my itunes library on my comp? cuz i just have it set to manually manage music. would it be easiest just to resynch the songs over after i update the album art or is there a way to synch the album art over without deleting all my music, or setting it to automatically update my songs (cuz i have a ton of songs on my comp)