@Broen:

The problem here is that you have a different understanding of "appropriate End functionality" than Apple Inc. does. according to Apple, Home and End are not supposed to move the insertion point, but rather scroll the window all the way to the top and bottom respectively (Page Up and Down behave the same way, but scroll just a page at a time). All of the apps that follow Apple's HIGs work this way (this includes Textmate, Safari, and Terminal -- the reason they appeared to do nothing is because you must have been scrolled to bottom of the document already). If you want to move the insertion point, that is where the {,Cmd,Opt}-arrow keys come into play (although, it seems that no one does Cmd-{left,right} arrow right, which should move to the end of the line, then on the next press, move to the end of the next line, and so on). The apps that behave differently (Dreamweaver, Entourage) do so because they chose to not follow the guidelines.

Now then... there's the issue of Cmd-{left,right} arrow not working in Terminal/iTerm. The reason for this is due to the nature of the applications themselves, which is to mimic the behavior of various terminals. These terminals that they are emulating likely don't have keybindings for things like Cmd-{left,right} arrow, and the app designers decided to not add those bindings for one reason or another -- probably because the various shells have different keybindings for this functionality (usually ctrl-a and ctrl-e) that people used to working in those shells would be accustomed to, and so they reserved it for some other use (e.g. iTerm uses them for switching between tabs).