I am just noting these here kinda for reference; so I can remember all the things that bug me about Mac OS X, primarily as differences from Mac OS.
I don't know if I've mentioned it before, but the black I-bar cursor in Mac OS changes color as it passes over dark backgrounds. Now, in BBEdit in Mac OS X, it still does this, but in other apps it doesn't. I don't think it is Carbon vs. Cocoa, because other Carbon apps don't. The I-bar instead has a grey shadow or something, which makes it very difficult to see when the entire background is black. I often lose my cursor in Mac OS X.
In many text boxes (such as cmd-~ from the Finder, to open a named directory, which in itself is cool), if you arrow left or right, the cursor disappears until I let go of the arrow key. So I can't hold down the arrow and move the cursor to a specific location, as I never know when to stop. Very annoying.
I don't know of any way to do custom contextual menus. In Mac OS, I have these little files to handle all sorts of things; for instance, I can ctrl-click on a file and select "Open Using -> file2clip" and it puts the path for that item on my Clipboard. Or select text and choose "CPAN" and it will automatically search for that text on search.cpan.org. That is something I use a lot, and it doesn't appear to exist in Mac OS X.