The Wii U eShop already offers a number of strong indie games including Chasing Aurora, Nano Assault Neo and Little Inferno. This is just the start of support for the digital store. Other titles such as Cloudberry Kingdom, Mutant Mudds Deluxe and Toki Tori 2 are on the way.

Art Academy: SketchPad (Nintendo)
Bit.Trip Runner 2 (Gaijin Games)
Chasing Aurora (Broken Rules)
Cloudberry Kingdom (Pwnee Studios)
DuckTales: Remastered (Capcom / Wayforward Technologies)
Fist of the North Star: Ken's Rage 2 (Tecmo Koei)
Kung Fu Rabbit (Neko Entertainment)
Little Inferno (Tomorrow Corporation)
Mighty Switch Force: Hyper Edition (Wayforward Technologies)
Mutant Mudds Deluxe (Renegade Kid)  [EU: TBD, NA: 13/06]
Nano Assault Neo (Shin'en Multimedia)
Pokemon Rumble/Scramble U (Nintendo) [EU: 15/08, NA: 29/08]
Puddle (Neko Entertainment)
Spin the Bottle: Bumpie's Party (KnapNok Games)
Star Wars Pinball (Zen Studios)
The Cave (SEGA)
Toki Tori 2 (Two Tribes)
Trine 2: Director's Cut (Frozenbyte)
Zen Pinball 2 (Zen Studios)

Giana Sisters: Twisted Dream (Black Forest Games) [EU: 22/08, NA: TBD]

TNT Racers: Nitro Machines Edition (Keen Games) - [EU: TBD, NA: 26/09]

8 Bit Boy (Awesomeblade Software)

A World of Keflings (NinjaBee)

Aban Hawkins & the 1001 Spikes (Nicalis)

Angry Video Game Nerd Adventures (ScrewAttack Games)

Anima: Gate of Memories (Anima Project Studio)

 A.N.N.E. (Gamesbymo)

 Another Castle (Uncade)

Armikrog. (Pencil Test Studios)

Armillo (Fuzzy Wuzzy Games)

Ballpoint Universe (Arachnid Games)

Biker Bash (Slightly Mad Studios)

 

Blood of the Werewolf (Scientifically Proven)

C-Wars (Onipunks)

Citizens of Earth (Eden Industries)

Coaster Crazy Deluxe (Frontier Developments)

Cosmic Highway (Maestro Interactive Games)

Cryamore (NostalgiCO)

Darts Up (EnjoyUp Games)

Days of Dawn (Bumblebee Games)

Dungeons & Dragons: Chronicles of Mystara (Capcom / Iron Galaxy)

Dusty Raging Fist (PD Design Studio)

Fade into Darkness (Maestro Interactive Games)

Festival of Magic (Snowcastle Games)

Forgotten Memories (Psychoz Interactive)

Ittle Dew (Ludosity)

Liege (Coda Games)

Monochroma (Nowhere Studios')

Mysterious Cities of Gold: Secret Paths (Neko Entertainment)

Noctemis (Lacuna Entertainment)

Oddworld: New & Tasty (Oddworld Inhabitants/Just Add Water)

Oddworld: Strager's Wrath HD (Oddworld Inhabitants/Just Add Water)

Oliver and Spike: Dimension Jumpers (Rock Pocket Games)

Pac-Man Museum (Namco Bandai Games)

Percy’s Predicaments (Maestro Interactive Games)

Pier Solar and the Great Architects HD (Watermelon Co.)

Project CIDER (Astrogun)

Project Y2K (Ackkstudios)

Putty Squad (System 3)

Q.U.B.E. Director's Cut (Toxic Games)

Road Redemption (DarkSeas Games)

Scram Kitty and his Buddy on Rails (Dakko Dakko)

Shovel Knight (Yacht Club Games)

Spot the Differences: Party! (Sanuk Games)

Soul Saga: Episode I (Disastercake)

Squids Odyssey (The Game Bakers)

Star Beast: The Stellar War (Pixel Entertainment)

Super Ubie Land (Notion Games)

Tengami (Nyamyam)

Terra Incognita (BackToBasicsGaming)

Teslagrad (Rain AS)

The 90′s Arcade Racer (Nicalis)

The Pinball Arcade (Farsight Studios)

The Unlikely Legend of Rusty Pup (Gory Detail)

Two Brothers (Ackkstudios)

Unepic (EnjoyUp Games)

Nicely spotted! I just copied the list from the source, but updated it with your comment.

Might as well keep this list up-to-date whenever announcements are made.

Mighty Switch Force 2 was announced a couple days ago.

Only for 3DS though. No Wii U version in the works yet, but not out of the question, either.

@OT, isn't Runner 2 already out? It's not an "upcoming game."

The 90's arcade racer, but thats not until the end of the year

oh thats on the list, ill get my coat :(

It's out in the States, but still not here... likewise Zen Pinball 2 is out over here and it hasn't crossed the pond yet.
So I've made a released list for those titles !

And just added Another Castle (by David Byers) to the list.

Play the prototype: http://www.anothercastlethegame.com/

http://www.kickstarter.com/projects/uncadedave/another-castle

How good is The Cave. The demo seemed fun and I am tempted to buy it. I liked Trine2 and have also considered Nano Assault Neo. I'm kinda waiting on them to go on sale first though.

I have ~$19 in my eShop account currently.

^ I'm not sure superchunk, maybe someone else can help you with that one.

I've updated the OP with links and some nice pictures :D

Wii U is getting a lot of Indie support. A few of those games really interest me. 90`s arcade racer really brings back memories. Which Sega would release the two Daytonas on eshop... or even a new one!
There are so many arcade titles to would be great on eshop.