Today, I just found about about code folding within Vim.
I have been using Vim for about 15 years, and use it very regularly for coding.
Today, I was using it trying to debug a long block of code, with many nested blocks, and suddenly wished that Vim offered a feature that is standard with graphical IDEs: the ability to fold nested code of blocks. I quickly searched the web and found that Vim has supported code folding since version 6.
Basically, the feature has been available all along, and for all these years, it could have made my job much easier, but I was never aware of it.