Call me a boor, but I haven't yet found an "extra" that's compelling on the disks. Given that English is my primary language, seeing 2001: A Space Odyssey in French didn't do anything for me. I don't see much point of watching the theatrical trailer when you've got the whole movie to watch, and turning on the director's commentary is just like MST3K, only not entertaining in any way. Seems like folks are just going wild trying to find ways to fill up all the space on the disk, no matter what it is.
P.S. the "we'll match any gift promotion" was pulled after about two days, so don't bother asking me how to get your own DVD for $95
On another note, I'm currently simplifying my stuff. As usual, some of my original designs are monuments to overengineering, so I'm replacing my old faithful self-growing array with a simpler design. I'm following a rule-of-thumb that someone posted in C User's Journal a while back, and it's working nicely. . .
1. If you add an item that causes you to have to grow your array, grow it to double its current size
2. If you remove an item that causes your array to be 3/4 empty, reduce the size by half
This seems to work quite well. It can be wasteful of space, but that's not a real problem for me, as the dynamic array I'm making only stores pointers. Worst waste I've seen so far is a few hundred bytes.