GitHub has a few tiny bugs that could probably be fixed with a few lines of code within a day (best case scenario), but they haven't for months now since I've reported these issues. http://shurcool.github.io/bettertogether/
The latest version of Chrome for iOS has a shadow not appearing properly when you open a new tab in the background. Once you switch to it, it's fine.
Chrome [1] for OS X has a small area around the close tab button where the hover animation occurs (button highlights red), yet clicking the mouse does nothing. You have to move the cursor a few pixels closer to the center before clicking will have an effect. This discrepancy between hover and clicking action is annoying because I often (several times per day) run into it. OS X dock has a similar issue.
I'm very picky when it comes to the smallest details... I'd rather fix them and move on than keep running into them every day.
[1] I know this one is open source, but because it's a huge project, I never got around to compile it, etc.