Patches are good; pull requests are even better =]
The XPI and CRX generation scripts would be great, I'm sure. I won't use them personally, but people ask for those all the time.
Come on, everyone, when you have things like this don't keep 'em to yourself ;-) Perhaps we should add a contrib/ directory to the repo for scripts and such like this that may not integrate cleanly into the build process but are still easy to use. Another possibility would be to add links to gists to the wiki.
Richard