Addicted to Curry
Ai Yori Aoshi
Ashita no Yoichi!!
Bad Company
Detroit Metal City
Gacha Gacha
Golden Boy
Hayate the Combat Butler
Historys Strongest Disciple Kenichi
Ichinensei ni Nacchattara
Mr. Full Swing
My Name is Zushio
No Side
No Bra
Otaku no Musume-san
Puri Puri
Rappi Rangai
Rosario Vampire
Saru Lock
Seto no Hanayome
Shounan Junai Gumi
To-LOVE-Ru
Tuxedo Gin
Wild Life
Yoo Ah Dok Jon
Yume de Aetara
Zippy Ziggy

SeeYa

Gorath

Hyakko, Sayonara Zetsubou Sensei[the teacher is suicidal, but for the most stupid reasons XD], Azumanga Diaoh, Pita-Ten... Actually, all of Koge-Donbo*-sensei's works are happy... 😃 You can also try Naoshi Komi-sensei's works, most of them are pretty funny.

Yokohama Kaidashi Kikou - really lighthearted story. It's like Yotsubato! in that I find it hard for someone to not like it.

Densha Otoko - Net Hatsu, Kakueki Teisha no Love Story - in the spirit of a classic loser to non-loser story, though this supposedly happened for real.

"When we remember we are all mad, the mysteries disappear and life stands explained."

• Samuel Clemens/Mark Twain