Auto-generate builder pattern; and maybe other common patterns?
I like to use the builder pattern when I have a class with a lot of different options. However, it is tedious to type it all up, even with copy-pasting the skeleton from elsewhere.
At the very least the skeleton of the builder pattern could be easily generated automatically. But probably the whole thing could be generated as a starting point like "generate getters and setters" and "generate constructor".
If we think about it there are probably a lot of other similar things (e.g., other patterns) that could be auto-generate to save time and make things easier / overcome language limitations.