I haven't seen anybody mention it before but the OSX calculator has been dramatically improved.
It used to be a simple toy that really didn't sastisfy my needs. (Did it even have a pi button?)
Now it has a scientific calculator that is more or less on par with windows but it adds some nifty conversion functionality and a paper tape.
It's made my morning.
500 mhz iceBook- 384mb ram, combo drive
One feature I wish it had is the ability to convert decimal values into binary and hex and vice verca. This would be a big help to me considering I have to do a lot of converting of decimal to binary in my Network+ class.