Recently, I was asked to write an essay and to number its paragraphs. I couldn't
find anything premade, so I worked something up using the ledmac
package. It isn't perfect (you need to restart it after using the
quote environment, etc.) but it did the trick for a simple essay.
In case anybody else is looking to do something similar, here's how I did
See the instructions in the comments for having numbers in the margin.