On usability conventions
I’m using MacOSX for three or so years and still admiring its beautiful interfaces and elegance. I have no GTK/WxWidget/QT and other applications. Most of OSX applications use native UI toolkit or at least look like native. And most applications do behave as expected.
But sometimes I feel gauged. This happens when I need to switch between tabs in some applications. To siwtch using keyboard shortcut. And here I get confused.
Here is a comparition table of applications I often use:

So I have three application with absolutely different and non-intersecting tab-switching shortcuts. But browsers do behave as expected on two common keybindings.
People developing browsers think on how the end user will switch between tabs, I mean they try to forsee what she would be comfortable with, and as result we have tha every browser supports most used shortcuts.
We really have to have a standart for tab-switching shortcut. Because it is a nightmare when you switch from browser to any other app and sitting and trying to remember how to walk between tabs in _this_ application. And can you imagine what a pain is daily using of Skype/Adium/Textmate/Google Chrome together?