Dangu (Nexgear) and Shin Angyo Onshi are two manwha with really stunning artwork (very realistic, kinda like Vagabond's artwork except less scratchiness and more delicate, detailed inkwork) and shounen storylines, both in the fantasy/adventure/fighting genres. Bishies of every gender abound *cheers* and the pacings are quite slow and careful (the fight scenes tend to be long but interesting) but you get the sense that they have very lush storylines, intricate worlds, and rich characters. Not intentionally "meaningful" and blah-blah "deep", just really great storytelling.
I've always wondered why 20th Century Boys (Manga-Heaven) doesn't get a bigger fandom. Granted, I can't see myself doing fanfiction/fanart for it, probably because the story is sooo freaking good and complex that I'm at the edge of my stool speed-downloading chapters. The only reason I'm not reading it right now is because I've heard that the ending, quite frankly, sucked (there were rumors that the mangaka just got bored with the story and no one even found out who "friend" was). But go read the first 20-something volumes anyway, the storyline feels spielbergian (except with truly evil kids and less sentimentalism) and the plots are amazing. No pretty bishies in this one I'm afraid, which might be why the fandom's limited.
Katekyo Hitman Reborn (KEFI - direct dls are available) is a shounen series that nevertheless caters chivalrously to yaoi fangirls, despite the one really-hot-chick-on-a-motorcycle next door. Basically, the story revolves around the wacky misadventures of a loser high school student (think Sena, only even wimpier) who, in the course of a day, gets told by a baby with a giant head and suspicious weapons(supposedly his new tutor) that he's actually the 10th heir to a famous Mafia family and that the hitman baby is going to train him to become a Mafia head, and then gets shot o_o. Much funnier and randomer than Bleach or Naruto, I can see a lot of possible fanfiction for this series because of its random bishies (OMG LAMBI-TEN-YEARS-LATER IS SOOOOO HOT XDDDD).
For an INSANELY funny manhua series from Taiwan, YOU MUST MUST MUST READ BOWLING KING (from Null, I can give the website address if you can't find it). The artwork ain't pretty and neither are the "bishies", but the story's just so f'ing hilarious that it's impossible to describe. Think bowling is for creepy old men in ugly shoes? Don't think at all! (I can guarantee you won't be able to after reading this manhua.)
For a better-drawn, not-quite-as-insane, very-shounen sports manga, hop on over to Over Time (KO-scans and Jump-scans). There's only a few chapters so far but it looks promising, bishie-wise, and the theme is pretty obvious (blahblahKoushienblahblah), but it reminds me a cross between Mr.FullswingxES21xHikarunoGo. I love Hikago and ES21, so I'll always be biased towards them and say OverTime isn't nearly as realistic or "refined" in storytelling techniques, but the promise of bishies is always enough to make me latch onto a fun series with decent artwork.
That's it for now, I'll update more later. Oh, and might I rec reading "Legend of the Condor Heroes" and its sequel "Return of the Condor Heroes" (which I'm reading and watching now)? The translations are decent, considering these are online, and they're fun reads!! The books themselves, by Jin Yong, are of course beloved and very popular series. I love wuxia novels and martial arts manga, so I'm always on the lookout for more. =^^=