There's a lot of openings and endings that I like but one of my favourite openings is that of Tenjou Tenge...it's just awesome even though apparently the anime is nowhere near as good.

http://www.youtube.com/watch?v=4YUWD4BZ81Y

I think Loveless ED is pretty and the OP to Magipoka, even if that anime is rubbish and silly the OP is dark and pretty.

Hmm... I really like the opening and ending songs for Gravitation, Love Hina, and Death Note a lot. They're all unique in their own way (well, despite the fact that DN's opening and ending were by the same band, Nightmare), and I really couldn't choose any single one between the six songs that I could really call my favorite as far as an anime opening or ending. xD I'm so indecisive, lol. xP

Yubiwa from Escaflowne is definitely the most beautiful anime SONG I've ever heard - just had to put that out there.

But I agree the ending of Outlaw Star was pretty nice.

I also love the 2nd season opening to Death Note, it's loud flashy catchy, but not obnoxious. Beautiful might not be the ideal word I'd come up for it... But it's really enjoyable.

i dont really know cause i like a lot of anime OP and ED.
but right now some i can think of is D.gray-man and the fan made opening of Naruto with the FAT sakura

I think the most beautiful Openings are:

Ghost in the Shell: SAC 2nd Gig [Watch the Opening]

Himiko Den [Watch the Opening]

Haruka Naru Toki no Naka de TV [Watch the Opening]

Pretear [Watch the Opening]

And it's not really that beautiful but...
I really like the OP of Mamotte! Lolipop because the song is so fun :) [Watch the Opening]

Enjoy!!

I've heard so many it's near impossible to choose! But I guess for now the final ending to Revolutionary Girl Utena. http://www.youtube.com/watch?v=elG2L2VKSgg

Jigoku Shoujo (All of them, openings and endings.) and Elfen Lied's opening are defiantly by far my most favorites.

Originally Posted by Anahita

Ghost in the Shell: SAC 2nd Gig [Watch the Opening]

I was thinking that one, myself. :3 I love it. I'm also particularly fond of the first opening...which also NEVER gets old for me. X3

The Stand Alone Complex movie (Solid State Society) has a pretty damn awesome opening, too.

Ghost in the Shell is just amazing. D:

I like a lot of openings >__>;
Paradise Kiss [opening]
Super Gals! [1st opening]
Kaleido Star [1st opening]
Nana [all openings lolz]
Magic Knights Rayearth [1st opening]
Ah! My goddess [1st opening] <-- It's so calming :3

Ouran Host Clubs opening and endings was probably one of the best.
They truly did describe the whole series.
I just love who they did the guitar solo while the anime was still playing at the end. I just gave the extra push for such amazement. But that's only because I love the series.

My favorites:
Paradise Kiss-Lonely in Gorgeous
Nana-Rose
Ouran Host Club-Sakura Kiss
GinTama-Pray

Elfen Lied was a beautiful beginning. It did get sort of boring after a while, but when you first watch it you are like pretty amazed by it.

I happen to think that Wolf's Rain had a beautiful everything. I'm sure not most people thing that, but I adored it.

http://www.youtube.com/watch?v=sbBKT8kx89c
^The second ending of Tsubasa. All of the main characters are all children. It's so cute. I remember watching it everyday. xD.
The music is just exquisite too.

my favorite music is defiantly the opening to .hack. Other favorites that I feel describe the series is like the last exile opening. Also a really catchy one is the blood+ second opening, done by hyde, and all the dreamers the yakitate second ending theme.

Your Nadesico warning is true!

In my opinion, the ED of Uta-Kata, "Itsuka Takeru Namida" (someday the tears will cease) by Savage Genius. YouTube for it, it's quite moving.

I really the opening to Moribito. The animation is done very beautifully and I really like the song as well.

http://www.youtube.com/watch?v=jpio7eGL9Mg

Hmm...long time that I didn't think about them. I used to love Fullmetal Alchemist's last opening, Rewrite and Kenshin's first opening, Sobakasu. As for endings, I'm not sure, I always loved openings than endings, I don't know why. Maybe the first ending of Card Captor Sakura, Groovy.

I have to actually choose? XD I'll tell you my favorites:
1. Catch You Catch Me- Cardcaptor Sakura
2. Futatsu no Kodou to Akai Tsumi- On/Off (Vampire Knight)
3. Monochrome no Kiss- Kuroshitsuji
4. We Were Lovers- Gankutsuou
5. Chouwa oto ~with reflection~-Gin-iro no kami no Agito
6. Sakura Kiss- Ouran Host Club
7. All Yu Yu Hakusho Opening and endings <3
8. All opening and endings from Nana

The opening for Fruits Basket. It makes me SO happy! ^_^

Sengoku Basara opening. Who can resist dancing samurais?

One of the ending theme to Chobits, Ningyo Hime. It's just so pretty.