Local Co-op games with same keyboard?

Tappo Tactics

Well Boxheads 2play is a sweet game to troll your friends with or just mess around in. Oh right and also there's the game :P

Killing zombies with upgrade depending on streaks etc

Thats all I can give for online flash games

I'd recommend getting a controller for one player and having a keyboard for the other - that tends to work better.

Awesomenauts. A hundred times Awesomenauts. Think side scrolling Dota with local co-op. You can play with up to two other people on the same computer.

Look for coop flash games in http://www.kongregate.com/ or any other flash games site.

i haven't played so can't tell if its good but Dungeonland seems to be a fun game with local co-op

Shuggy

Fallout New Vegas has a co-op mod.
Mod

Motherfucking Worms series.

Tobe

Also here on nitrome. I really like their games, not only multiplayer, but multi are really fun.

cortex command

Jamestown is a really good one.

Castle Crashers

You can always play King of Fighters or Metal Slug, just plug 2 keyboars so will be easier to play and configure different keys

LEGO!

Lego LOTR is one

Pid clicky

Jamestown.

Worms, Need for Speed 2 (don't know for the others), Heroes of Might & Magic III.

The bomberman games on snes, pretty much all snes games

Gatling Gear

rubber ninjas is awesome, I have been playing that game with my friends recently and we all love it :D
http://rubberninjas.com/

Kung fu strike! <3.

Don't know if it also support co-op, but you can fight against each other on the same computer :3

Craftfighter - A minecraft fighter

It's free too

Little FIghters 2