As someone who has worked on simulated television effects for Atari games, I was happy to learn about Cathode, a "vintage terminal emulator" for Mac. It simulates phosphor burn, screen curvature, glare, refresh rates, beam desyncrhonization, jitter, and other effects common to mini-computer terminals of yore.

It's a functioning terminal program, so you can run any of your favorite UNIX command-line programs, or telnet into a remote system, or whatever. On first blush it might seem like a novelty, but the visual properties of terminal systems were indeed a part of their experience. Given the fact that operating systems like UNIX have been around for more than three decades, its easy to forget that the different input and output hardware on which they were used have an impact on the experience of using different computing systems.

Cathode is $20 shareware, and it has a lovely way of encouraging purchases: among the program's many configurable settings is "distress," which controls hue-shift, noise, and jitter. Those settings are disabled in unlicensed versions, and the quality of the display slowly degrades over time until the product is licensed.

(thanks to Torley)