Not really open source, but I feel like http://zisworks.com is an honorable mention. He does custom FPGA's for high resolution monitors. It isn't as impressive today, but he's built boards that are capable of doing 4k @ 120hz. What I thought was particularly cool was 540p @ 480hz. Its wild! I've never seen something so smooth! Its like I experienced true level [1].

[1] https://www.youtube.com/watch?v=Q1zBtJhgwBI