One of the more prominent family parts in the LEGO catalog are the Slopes. There's single and compound slopes, double slopes, squared cones, and inverted slopes. Then there're cousins to the slopes such as windscreens. There are even a few black sheep in other families who have slope qualities. Slopes have a name and a degree of slope but there are really two different numbers. Almost all slopes have a half plate lip at the end. Therefore the slope when stacked is actually a few points off. There's even one slope who must be undercover since it's name is not the same as it's inherent or stacked slope.
I've seen many resources on the web where families of LEGO parts are treated and explored. I've not seen one for slopes. Below is a link you can use to explore a chart that shows each type of slope, it's Bricklink name, assumed slope, actual slope, stacked slope (where applicable) and SNOT slope. There is a link to each part as well. The SNOT slope is what happens when the part is attached sideways. This technique allows for a few more slope angle options.
Since this resource is a dynamic spreadsheet you are more than welcome to request other related parts, another data column, or whatever fancies you. As it changes I hope this resource will become more and more useful. You may have also noticed that this is Slopes Part 1. What could possibly be in store for part 2?