The Mac Trash Bin

I hate to admit it, but Windows actually has one advantage over OS X, and that's the handling ofdeleted files.  Sure, on both systems you can always undo the last operation (well, not always... I'm not going to make that blanket statement).  However, Windows Recycle Bin has a few big advantages:

Windows Recycle Bin remembers where each file came from.
Just right click an item and choose restore, and it will go back to the right place.  Very important for those deleted preference files that need to end up in some arcane location in your Documents and Settings. In OS X, good luck placing stuff back in to the right folder. Strange that OS X is all about metadata but doesn't keep track of this.

You can selectively remove items from the trash
As opposed to OS X's all-or-nothing "Empty Trash" option.

When you're copying a folder and another of that same name already exists in the destination, Mac only gives you an option to Replace.
This deletes the existing folder then copies the new one in it's place (see common Finder gripes: "Replace vs Merge").  Something deleted in this way doesn't go to the Trash. This is insult to injury: Not only are you surprised to find that you just accidently did a delete and replace instead of the far more common and expected merge, but then you're double-screwed because Apple decided to disable Undo for this most destructive of actions.  It's pretty evil.

And to all the Mac users out there: all the other OS's do merge, or will at least give the option for it.  I'd at *least* like Finder to present this choice, especially since the Merge operation is a lot harder for a user to replicate on their own, than a Replace.  By the way, it's not perfect, but you can reclaim some of your lost Merge with MergetoFinder applescript