Ooooh, a new update!
Mamacolle - Boring shoujo story about a culture in which random blob-things called "babies" are kept as pets. The heroine gets some unique "babies". The babies are awfully cute, and I like the romantic interest, but it's definitely not worth reading.
Merupuri - Borderline shotacon. Still a fairly nice (and short) romance about a girl who gets dragged into a magical kingdom by a prince cursed to occasionally inhabit an adult body (he's a little boy). Worth reading, especially since it's complete at... 3 volumes, I think?
Midori no Hibi - Girl becomes boy's hand. A cute and complete comedy that probably isn't worth reading more than once, but I'd recommend it if you want a funny shounen romance that isn't an extreme harem.
Milk Crown Lovers - Well, you kinda need to read the previous two Milk Crown series first. =P Despite the name, it's a sweet shoujo romance. I personally love this series - the characters have some interesting personality quirks, and since the relationship is formed in the first Milk Crown, there's very little angst about "does he like me? does he not? =(". Oh, and there's a pet shark. A PET SHARK.
Monster - I didn't love this, personally, but everyone has read it so why not. It isn't bad or anything. Decent seinen mystery.
Muhyo to Rouji - Good Weekly Shounen Jump series. It's about a strange lawyer and his apprentice who send demons to Hell with their superawesome lawyer powers. It doesn't follow the usual shounen adventure series formula, and while it hasn't been scanlated very far, it's been quite interesting up to that point. Give it a try~
My Balls - Hey, if Digi reads it and thinks it's funny... Not for children or people who get nervous at the thought of reading about sex.
Nagasarete Airantou - I'm willing to read harem manga if they have decent plots (Love Hina, Ichigo 100%), but this did not. Unless you like loli-harems, don't pick this up.
...and those are all the ones I can remember.