Can anybody suggest good Ecchi/Harem manga?
 

I would Recommend these five
1) IO
2) Samurai Harem
3) Ninja Girls
4) Sekirei
5) Mouse

There's a Clannad manga?

Anyway I'm not one for ecchi stuff - except Highschool of the Dead because the gun porn offsets it dramatically - but I did enjoy "Yomeiro-Choice". I've only read five chapters so far but it's been pretty funny.

The best harem manga has to be Ranma 1/2.

All ecchi, not necessarily harem, but along the same vein:
Outlanders
Parallel
Pastel
Umi no Misaki
Pretty Face
Gacha Gacha - Secret

If you don't mind a supernatural twist and some fighting, I would highly recommend Rosario + Vampire

Also, a little similar to Love Hina in some ways but completely different in others in Asu no Yoichi

Ichigo 100% and Shuffle! are two good suggestions I can offer you :)

Nobody mentioned To-LOVE-Ru? Every single girl is hot, panty shots everywhere, most situations result in nudity, etc.

yeah i have read rosario+vampire that was the very first ecchi manga i read its superb:D

To-Love-Ru is one of the bests dude every girl there its like.. wow

Thanks yeah high school of the dead is creepy but everybody wants to rape the male protagonist xD and yeah there is a clannad manga:)

Something New? Otomari Honey...i'm not sure if its directly a harem but its ecchi with 4 girls or more living in one guy's house.

Thanks ill read that one!:D

Wassup guys keep them coming xD

Bokusatsu Tenshi Dokuro-Chan, very ecchi! :)

Shina Dark
Ani Hana
Ichigo 100%
Puri Puri
Rosario+Vampire
Ai Kora
Yume de Aetara
Pastel
Aki Sora
Tayu Tayu
Yomeiro Choice

Zero no Tsuakaima semi-fits your description, and has a pretty good story while its at it.

Omamori Himari
Hayate the Combat Butler
The World God Only Knows (not really a harem but it could be one later)
Nagasarete Airantou
Unbalance x2

I love R+V and i also enjoy these. These fit your description nicely.

Ranma 1/2- codifying and then parodying the genre at the same time

Weird that nobody has mentioned 'My Balls' yet.

A guy with a demon queen trapped in his balls makes a harem of the entire underworld in 30 days. The problem is he cannot ejaculate.

The most hilarious ecchi manga ever, its probably considered hentai if not for censorship.