I'm looking for some good series with a good number of chapter releases based on the aforementioned genres. Mostly I'm interested in action/martial arts, but I have enjoyed several sports or other manga that had great character development. And by character development, I mean the main character is developing/training/improving his physical/mental skills through hard work or practice, and typically uses those skills to challenge and overcome other people or obstacles. While this doesn't have the be the primary element in the manga, if it has a good amount it's a-ok with me

And yeah, it sounds picky, but I'm not a fan of completely unrealistic gains or improvement like that seen in HunterxHunter or Shaman King. They were still great but that's not what I'm looking for ;)

I'd like to avoid any manga that has this kind of thing in its description: "...stumbles upon a weird girl with special powers". OMG this kind of thing is overused and annoying. This'd probably rule out most ecchi mangas as well

Some series I've enjoyed extremely (to give you an idea):
Shamo
Vagabond
Berserk
Slam Dunk!
Change Guy
Noritaka
Eyeshield 21
Rookies
Beck
Hikaru no Go

Others I've enjoyed somewhat:
Hajime No Ippo
Grappler Baki
History's Strongest Disciple Kenichi
One Piece
Air Gear
Major
Ryurooden
Tenjou Tenge

...And probably several others

I hope you guys can suggest some ones that have been hiding from me! I've read so many along these lines that it's become difficult to find any good ones with a decent number of releases.

Currently checking out: Garouden, Vinland Saga, Rookies (catching up)

It doesn't exactly fit the mold, but a manga that does sort of have a guy training/improving, and also a good deal of character development in the more usual sense, is Hanaotoko.

(And even if it's not a perfect fit for your query, it's an absolutely awesome manga and you should read it anyway.)

Holyland
Ookiku furikabutte

________________
This week's favorites:

- Golden Kamui





ççççççç[Ô .Ô] tsutopodus© will eat your manga and steal your cats!

Piano no Mori

Shounen, but probably fits the bill:
Me Gumi no Daigo

Ubel Blatt

Gantz

Riki-Oh

Aiki

Sidooh



________________
LOOK AT MY WITTY SIG!!11!!!!11

You can try:
Beach Stars
Samurai Usagi
Open sesame
Worst
Crow