Can you list some very unknown (yet really awesome, or just good and funny) anime?

Sora no Woto/Sound of The Sky. It is one of the most beautiful anime I have ever seen, and I recommend watching it no matter what sort of anime you like. Sorry for lack of current picture; I'm on mobile. Here is a description:
Sound of The Sky is a story about a young, 15 year old girl named Kanata. When she was a little child, a beautiful woman played 'Amazing Grace' for her on the bugle, and ever since then, she had wanted to learn to play the instrument. In order to receive training, Kanata joins the army, seeking to, one day, play Amazing Grace. Please watch it! It is truly heartwarming and sweet, and it brought me to tears. Even brought my older brother to tears. ;)

Kimi ga Nozomu Eien

While it's not like it's underground, Akira's a great movie/manga. It was super popular in the 80's and was largely responsible for introducing anime to the west! It definitely lives up to the hype. The picture I'm attaching is of my favorite character from it, Kaneda!

Serial Experiments Lain is relatively unknown, but I see that there is a small fan following on here. Came out in the late 90's.

The Macross series is supposedly really good! I haven't watched it myself, but the music and art is gorgeous from what I have seen. That one's also kind of old.

JoJo's Bizarre adventure (2012) it has a pretty solid story, like able characters, and good comedy. Some may not like it because it is very over the top compared to others, but it's worth it

The Gokusen
Bastard!!
Trouble Chocolate
Nanaka 6/17
I My Me! Strawberry Eggs
A Wind Named Amnesia
The Curse of Kazuo Umezu
Twelve Months
The Fantastic Adventures Of Unico
Virtua Fighter

fruits basket

It's not really thaaaat unknown but not too many people have seen Claymore and it's an amazing show.

Also not many people have seen Juuni Kokuki, probably because it's on the older side, but that's also a really good show.

· Magic User's Club (Mahō Tsukai Tai!),
· The Rose of Versailles,
· Maison Ikkoku,
· Seven of Seven (Shichinin no Nana),
· Osamu Tezuka's Kimba the White Lion and Princess Knight,
· Super Gals! thanks to my sister, I love that show.
· Cat Planet Cuties,
· Shrine of the Morning Mist, and...
· Gegege no Kitarō. The franchise is REALLY popular in Japan, but surprisingly unknown in North America.

Unlimited Fafnir