Kami nomi zo Shiru Sekai, Yamada-kun to 7-nin no Majo Recommendations
Yamada-kun & TWGOK share similar plotline of accidentally dealing with supernaturals and the mission of "conquering" girls by kissing them which indirectly adds to a hidden harem. MC gets dragged from their comfort zone and by the end has their life changed by interaction with others. Only difference is the MC is either an otaku vs delinquent.
Both involve the main character going around a school setting searching for girls who have a tie to the supernatural. In The World God Only Knows, it involves "conquering" girls in order to get the bad presence out of them. In Yamada and the 7 Witches, they are trying to find the witches in the school. Both involve the kissing of the found girls to resolve plot. All in all, I did enjoy both shows and I definitely recommend them.
Instead of simply pointing out similarities, I'll put it in a different way.
Yamada-kun to Nananin no Majo and Kami Nomi zo Shiru Sekai form a new genre themselves. We're yet to see more like this, but somehow the idea both of them have is appealing. Approaching to the Harem genre in such a distinct way, without having a girl falling in love in each episode because of the MC's generosity, the lead ends up being "forced" to get the girl of the episode. That is, if it's only one episode for that girl. Unfortunately Yamada-kun is apparenty getting only one season(I think) but if you
Romantic comedies, with the same 'let's grab dem chicks' rythm to them. Kami nomi requires some effort to get through all of the seasons, while Yamada-kun has a simpler and tighter narrative where everything is pretty much resolved by the end.
Likeable casts with, uh, quite unusual leads. Drama/silliness are balanced well, and both have solid scores to back them up. Good stuff.