I'm not trying to BigUp Lil Jon or anything because I cant stand his Muppet-looking ass.
BUT, the reason he is credited is because that is his beat and he is the producer of that song. Im getting sick of him, but I know of at least 4 or 5 top 10 songs he has produced and screamed over since last summer, and every rap group out right now and many r&b cats are coming out with Lil Jon produced singles. If you look at any Billboard charts its harder to find songs that arent Lil Jon than the ones hes on. Lil Jon= hip hop that is basically screaming over Techno beats.