[NOTE] - Using the Overclocking forum for now due to the nature of this, even though it is a GPU based system.
Now, we've heard of Pixel overclock and just overclocking the GPU - this method, while rather simple (assuming you have an Nvidia GPU, or AMD GPU and know how to find these settings) is really not quite overclocking.
FIRST THING, HUGE, LONG-WINDED DISCLAIMER
I'm not responsible for breaking things. I haven't broken anything (permanently, at any-rate) however I have ONLY tested this on windows 7 on my personal machine, however due to a small group of friends having a seemingly limitless number of downloads, it will work on most, if not all, Linux distros (including Mac (It's BSD... really it is) and Debian). I do NOT know however if it works on Windows 8, I do know that it will NOT work on windows Vista (I know not why). I have no personal test data for windows XP. Again, if something is broken, you need to boot into safe mode, or your hard drive suddenly floats off into space, it is not on my part.
Now that that is out of the way; HOW TO DO THIS!
This uses a long known technique called Downsampling. The name is actually a long form of Anti-Aliasing, (Ordered Grid Super Sampling Anti-Aliasing), but we'll call it downsampling it for short. No, not OGSSAA. No.
Anyway, this takes advantage of the fact that quite a few monitors can be forced to render resolutions that are higher than the actual pixel count on your screen through the video card. I've gotten some abnormal sizes, but I recommend looking at <A href="http://en.wikipedia.org/wiki/List_of_common_resolutions">this link</A> for a list of common resolutions to set yours to, in order to prevent nasty bugs that occur with abnormal resolutions (most notably, Fire-wall and other notifications that come up from the taskbar being off-screen and un-clickable, some Direct-X instances not being able to render into the screen properly, so-on, so forth).
Oh but how do you do this?
In NVidia Control Panel, got to the Change Resolution, click the customize button.
In the dialogue box that pops up, click Create Custom Resolution.
Here, experiment - if you get a black screen, merely hit escape once to go back and change the settings.
Figure out the largest resolution you can handle, then look at
http://en.wikipedia.org/wiki/List_of_common_resolutions
for a common resolution to fall back to (to prevent aforementioned bugs).
{NOTE}
You can toy around with some horizontal and vertical settings. I have a maximum hat's 1.5 the times of my native 1366x768 (2049x1152), as well as 1920x1200 - a 16:10 resolution on a native 16:9, so there are black boxes around the edges, but I don't need to worry about the notifications causing errors on my desktop, however, since the 2049x1152 resolution is saved to windows thanks to the Control Panel, I do drop it to 2048x1152 and change it to that in game. I tried going to 1200vertical on anything higher than 1920 (so I could get a 1200 vertical on a 16:9) but it wouldn't function on my specific monitor. Test. Play around. Test.
Now, what does this really do, and why would you do it?
Well some games have bad AA built in, don't have any way to 8x,4x, or 2x it, or don't have it at /all/.
This changes that by forcing the graphics card to either use untapped potential in older games, or be overclocked in modern ones, to render the screen at, say, 1080p or 4k, and then downsample it for the monitor in question, resulting in smoother lines, softer edges, and more natural curves. It's a form of, as the title mentioned, super-sample AA, and allows some crazy good looks for your games. Depending on your setup (monitor and card/cards), you can actually render the game in 4K and display it on a 1080p screen to get this extreme level of AA.
{{NOTE NUMBER 2~!}}
This works with, and blends incredibly well with, in game AA techniques. It increases the strength of the AA, however, some games have poorly optimized AA methods, or break in game filters. Downsampling does NOT interact with these filters - remember, the game merely thinks it is rendering at the higher resolution, and can use more pixels to create these smooth curves. Post processing effects, like shadows, or night vision, or other things of that nature, won't have a chance to break or cause abnormal glitches.
I hope you all enjoy this guide, as I didn't see one on these forums and was surprised by it. It's not a difficult way to squeeze performance and graphics quality out of a card for older games (Halo 2, other semi-recent games that just don't have the AA options and such (Half-life 2, TF2, L4D2... these look /beautiful/)), or just getting more screen real estate on a cheaper, smaller screen.