Used this on another forum, and I'm copying it since I'm too lazy to retype another one personalized for ya *-* This person already watched some popular shounen that I left out, so... sorry that I leave out important ones xD
Hope it helps though.
If you're into action,
Katekyo Hitman Reborn! is a good shounen that's pretty long...
Gurren Lagann is a shorter series, but also good and popular. I haven't watched it, but it includes mechas...
Darker than black is a lesser known series, but also pretty action-y. Watch the opening of it and you might fall in love oUo
Wolf's Rain is kind of long, lots of unneeded episodes, but again, ACKSHUNNNN and a lot of philosophical crap too. If you like wolves, you might like it.
Code Geass is somewhat popular, and also really good. So many plot twists, expected and not. It's sort of like Deathnote, but more 'colorful' and actiony, and with a bit of comedy every few eps to lessen the drama. The ending is so amazing though, I cry every time I see it ;u; (DON'T LOOK UP ANY SPOILERS FOR THIS SERIES IF YOU DECIDE TO WATCH IT!! OR IT'LL RUIN THE END DDD: )
Higurashi no Naku Koro ni (aka Higurashi: When They Cry) Is kind of a good horror one, though a lot of comedy and filler-like episodes. It might seem kind of girly, but there's also lots of gore
Paranoia Agent is also good if you want something creepy.
If you're interested in shoujo
Ouran High School Host Club and
Haruhi Suzumiya no Yuutsu (The Melancholy of Haruhi Suzumiya) are pretty well known. Ouran has a lot of comedy, and a wonderful ending!
Tsubasa Chronicles is really cool so far, though it's not strictly shojo, there's a love element to it. It hasn't had me screaming at the television yet like some awesome anime, but it's pretty decent~
Haibane Renmei is lesser-known, kinda old, but if you want something more philosophical it's good. Not so much action in it, but it's a pretty sad and also symbolic.
For Comedy,
Axis Powers Hetalia's awesome, but episodes are only 5 minutes
![^-^](https://www.kumoricon.org/forums/Smileys/default/azn.gif)
; There are 50 total, but I can only find a few online...
Sayonara Zetsubou Sensei's fun if you like things random, and it's... very random. No storyline. At all. But half of the episodes are really entertaining xD You could probably watch an ep between episodes of others.
Bokusatsu Tenshi Dokuro-Chan is only 4 or 6 episodes long, extremely funny, but also really perverted xD
AAAAAAAnd that's all I've got
![Cheesy :D](https://www.kumoricon.org/forums/Smileys/default/cheesy.gif)
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Oh wait, some other good older action ones are
Cowboy Bebop and
Trigun. They're both kind of a combination of 'Old West' with shootouts and stuff, and also Sci-fi. ... Well, Trigun not so much Sci-fi. I forgot most of it.