I will never get used to the trailing slash on source arguments in BSD cp (that copies directory contents rather than the directory itself)! The first thing I do on an OS X machine is install GNU coreutils.

Me either. I've also got a habit of adding '-rf' as the last argument to 'rm' so I can safely tab complete things in my home directory without a mistaken "enter" press nuking everything.

I'm used to that from rsync. I find it quite handy.

This may be why I never found rsync comfortable.