Koreans call web cartoon "웹툰Web-Toon" and
there're so many cartoons on Korean portal sites.
And some of them are really funny, some are sad, cool, lovely or boring. kk
I think it could be a good way to learn Korean, especially conversations and expressions.
And culture, of course.

Two biggest webtoon sites are DAUM and NAVER.
They're also the biggest portal sites in Korea.
Visit here : <a href="http://cartoon.media.daum.net/series/">http://cartoon.media.daum.net/series/</a>;
                    <a href="http://comic.naver.com/index.nhn">http://comic.naver.com/index.nhn</a>;

I recommend some webtoons here.

1. IKKI (The moss)
<a href="http://cartoon.media.daum.net/series/view/ikki/2">http://cartoon.media.daum.net/series/view/ikki/2</a>;

A man who destroyed his own life with obsession
comes to the country town for his father's funeral.
There's a secret in this weird town and its people.   
This is great thriller! I started to read Ikki and I coundn't sleep all night long.
It was made to movie recently. For advanced learner.

2. TIMING
<a href="http://cartoon.media.daum.net/series/view/timing/2">http://cartoon.media.daum.net/series/view/timing/2</a>;

There're some people who can stop the time, who can rewind the time,
who can see the future of 10 minutes, and who can see one scene of the future.
These people gathered to protect some tragic accident.
Horror(?). Some people wouldn't like the picture, but it has great story.
KangFull, the cartoonist is one of the most popular storytellers in Korea
and his comics are all made into movies or plays.

3. 생활의 참견
<a href="http://comic.naver.com/webtoon/detail.nhn?titleId=25613&no=267&weekday=sat">http://comic.naver.com/webtoon/detail.nhn?titleId=25613&no=267&weekday=sat</a>;

Comic.
I don't know how to translate it's title into English...
Humour is sometimes the most difficult part of the language.
I like this cartoon so I wish some of you can understand it and laugh out loud.

4. SNOWCAT
<a href="http://www.snowcat.co.kr/">http://www.snowcat.co.kr/</a>;

Snowcat is one of the "oldest web cartoonist" of Korea.
I don't mean she is old, she is one of the people who started web cartoon for the first time
and brought the wind of web toons.
She uploads her pictures and diaries and cartoons altogether,
so I think this is the easiest to understand.

5. 마음의 소리 Sound of the heart
 <a href="http://comic.naver.com/webtoon/detail.nhn?titleId=20853&no=449&weekday=fri">http://comic.naver.com/webtoon/detail.nhn?titleId=20853&no=449&weekday=fri</a>;

Well....I think no one here can understand what this cartoon says,
because even Koreans can't understand this cartoon 100%..kk
This is CRAZY and really funny. I felt like I could die while I was laughing.
 
6. 마조&새디 Majo&Sady
<a href="http://intelpc.shopping.naver.com/catoon/view.do?seqNo=2758&code=PCM004&pageNo=1&searchDiv=&searchWord">http://intelpc.shopping.naver.com/catoon/view.do?seqNo=2758&code=PCM004&pageNo=1&searchDiv=&searchWord</a>=

Comic. Majo is character designer&househusband, and Sady is his working wife.
Majo is also famous cartoonist and this cartoon is about their daily life. 

7. 루나파크 LunaPark
<a href="http://www.lunapark.co.kr/diary.htm">http://www.lunapark.co.kr/diary.htm</a>;
This is for ladies~ Luna is 28-yo and she has drawn her daily life for years.
Sometimes it's funny sometimes sad.
6 months ago she quit her copywriter job and started to travel.
Language is not that difficult.

8. 노란구미 Yellow Kumi
<a href="http://koomi.net/25552780">http://koomi.net/25552780</a>;
Kumi is Korean who was born and grew up in Japan.
As 3rd generation of Korean-Japanese family,
she feels like a stranger herself both in Japan and Korea,
because there's been discrimination to Koreans in Japan, and vise versa.
She learns how to handle this problem and
thinks about the relationship between Korea and Japan. 
Her Korean is very easy and you can learn the culture and history of Korea too.    

9. 신과 함께 With God
<a href="http://comic.naver.com/webtoon/detail.nhn?titleId=119877&no=2&weekday=thu">http://comic.naver.com/webtoon/detail.nhn?titleId=119877&no=2&weekday=thu</a>;

An ordinary man died and the angels of death come to bring his soul to the underworld.
He need to be on trials for 49 days, and a lawyer appears for his defense.
Their journey through 7 hells for judging his sin begins.

This cartoon is based on a traditional concept of death and hell in Korea.
But this is not horror. It's mixed with traditional and modern sense, parody and humour.  
Highly recommend! After finishing it you'll feel like you're a great sinner;-D

Hmm after writing all these recommendations,
I realized even the easiest cartoon could be difficult to understand for beginers..
But I hope you can understand one of these and like it!