I have a minor pet peeve.
Someone writes a really cool patch with includes a cool features that I want in my module. However, in the notes for the patch you'll get something like this (I'm totally making this up, no real people were harmed in the creation of this rant):
Here's my patch to make Foo transactions non-blocking if you're running under ithreads. I also reorganized the test suite so that it makes more sense.
Linus was right on one point; short, concise patches are best. I didn't realize that till I started being the person that accepted the patches, not the person sending them.