Multiple instances of ports/emulators/etc (for streaming)

[Bucket]

A friend and I want to ramp up our streaming channels and we'd like to feature mainly cooperative/competitive games. There are plenty of splitscreen multiplayer games to choose from but others require us to run the game on two machines. To get around this, there are a few solutions I know of: there's a port called Doom Legacy that allows split-screen play, and also an emulator called TGB dual that supports multiple instances to emulate Gameboy link play. I'm hoping these aren't my only options, as there are so many other platforms to stream for (not the least of which being DOS and Windows). I would love to, for example, do a co-op run of Half Life showing both our screens in the stream.

 

Can anyone recommend any other multiplayer-friendly ports or emulators? Alternatively, is there any software that can capture screen output from another PC on the network? If there's any software solution that doesn't involve spending over $100 on a capture card, I'm all for it.