Generally what is found in the Edit menu in applications is pretty standard, and I almost never poke around in there, because all of the necessary features are controlled by standard, easy-to-remember shortcuts. However, in my boredom one day, I stumbled upon what I believe is a new addition to the Edit menu in Tiger, the 'Paste and Match Style' option, invoked by the Command-Option-Shift-V shortcut. It does exactly what it says, and I've used it in TextEdit, iChat, and Mail.
This feature is very helpful for pasting things from websites that generally have weird formatting and colors (and require a lot of clicking to remove). I realize this isn't much of a hint, as the feature is in plain view for all to see, but I've been a Tiger user since the beginning, and I found it only last week. It's a little improvement that I've already found somewhat indispensable. Enjoy.
[robg adds: Yes, it's a menu item. Yes, it's plainly visible to all. Yes, I chose to run it as a hint, because a surprisingly large number of people aren't aware of it. It's not new to Tiger, though -- in Panther, it was called 'Paste With Current Style,' and accessed via the same shortcut. You'll only find this in Cocoa applications by default, though I suspect it could be added to Carbon apps as well, if the developers wished to support it. And please, save yourself the trouble of posting insightful comments such as "Hey, look at File: Save As, and Edit: Cut, and ...". If you feel this hint is too basic, just move along, there's nothing to see here :).]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060102005706421