Recommend me a manga, extra points if I haven't heard of it. GOOD LUCK!
The World God Only Knows.
AO no exorcist AKA Blue Exorcist
20th Century Boys.
Pokemon Special (sometimes call Pokemon Adventures)
"Pandora Hearts". Amazing art style and fun plot. Interesting, as well. Or you can go with something classic (assuming you don't know them), like "Gunslinger Girl" or "Rozen Maiden".
"Princess Resurrection" is a great title, too. Really fun and campy.
Yaoi related I'd go with 'Descendants of Darkness' (mild yaoi) or a really, really fun one, 'Antique Bakery' (little to no yaoi but fantastic setting and idea). Of course, these are just my suggestions.
Devil Survivor 2 The Animation XD
If you haven't read Dragon Ball, you're doing it wrong.