too all my fellow weebs out there, let your voices be heard!

https://www.youtube.com/watch?v=vZsgTwMIbn0

https://www.youtube.com/watch?v=7UPI17c48nU

https://www.youtube.com/watch?v=3TYjpNI5_bc

also gog add a embed feature, I don't get why that's not a thing by now

Blue Gender
Elfen Lied - even though it's sort of depressing :P

The forum is so bare-bones, I'm almost surprised they have bold, italic, underscore, and quote.
Look up Barefoot Essentials, and Adalia Fundamentals, they both add multiple useful functions to the site, including the forum. Among others, the option to view linked videos as if they were embedded in the post (I don't remember which of them does that, I think it's Barefoot).

Regarding the topic, Cowboy Bebop and Samurai Shamploo are up there, but recently, the theme to .hack//SIGN have been playing in my head.

I'm a bit of a sucker for this. High energy, and badass. (Sailor Moon Crystal)

Space Brothers


I'll be so unhappy when I'll be forced see all those embedded memes, videos, images, gifs and what not. GOG forum may badly need an update but its current simplicity is something like very much.

Technically not anime: Robotech.

Anime: Yu Yu Ha Ku Sho !

REDVWIN

Not much into anime, but alway love this.

Cowboy Bebop

I love these two:
Kill la Kill: Before my body is dry.
Shadow Skill opening.

Does this count?

https://www.youtube.com/watch?v=Z7jk4lKKmnY

let the voice of love TAAAAKE YOU HIIIGHHHERRRRR

I think late 90s and early 00s got the best OP/ED. Some of my faves:

One Piece: Ruppina - FAITH
Rurouni Kenshin: Bonnie Pink - It's Gonna Rain
Wolf's Rain: Maaya Sakamoto - Gravity (Written by Yoko Kano, the same composer as the Cowboy Beebop above)
SE Lain: BOA - Duvet

Just realizing that all that song above sung by woman. And always surprises me when popular western music made their way into anime like:

Higashi no Eden: Oasis - Falling Down
Jojo: Yes - Roundabout

if I'm not mistaken, Jojo's author Hirohiko Araki a big prog music fan.