Just a small offering this time: The pin light mode from After Effects is a conditional operator. For every pixel in each channel, if image2 > 0.5, display the maximum of image1 or 2*(image2 – 0.5). Otherwise, display the minimum of image1 or 2*image2. So put the following expression into each channel of a Custom Tool:
if(c2 > 0.5, max(c1,2*(c2-0.5)), min(c1,2*c2))
Or if you're feeling lazy, unzip this file into your macros directory: blend_PinLight
If I encounter the need for other AE/Photoshop blend modes, I'll expand the macro and update it here. I rather think it's getting to the point where I'll want to create a downloads page on this site instead of hiding all of these tools in blog posts.
Here's the Glitch_HumBar macro I promised in the comments: Glitch_HumBar
And Ribel's VHS_Glitch_Strip macro: VHS_Glitch_Strip
Ribel's macro has an instructive use of the Custom Tool. The NumberIn and PointIn controls are used to select the height and location of the tearing strip. Those numbers are fed into the Setup expressions, where they're divided in half, providing a distance above and below the point control. The Setup expressions run only once per frame, so getting that information there is more efficient than doing it in the other expressions, which evaluate once per pixel. It's just four simple operations, so the savings are minute, but it's good practice, anyway.