A lot of key emacs bindings--C-a, C-e, C-n, C-p, C-f, C-b--work in any text field (even, say, the Hacker News comment box). But M-f and M-b (which are really useful since they get you forward/backwards a word instead of just a letter or a whole line) don't work. When I try to type option and then a letter, I get weird symbols:
Here's option-b: ∫
Here's option-f: ƒ
To get make M-f and M-b work, go to Preferences->Settings->Keyboard and check the "Use option as meta key" box.
It has nothing to do with Terminal.app, but I consider the ease of making those symbols one of the nice things about text entry on a Mac—I miss it sorely on Ubuntu (where I'm sure the equivalent exists, but (1) I don't know it and (2) it likely requires memorising code points). You can see which keystrokes will produce which funny symbols by turning on Keyboard Viewer (under Input Menu, which itself can be turned on from the International tab under System Preferences.app; or there's probably some way to invoke it directly).
The list is a bit old, but maybe it helps with some odd keys. Now that unicode is pretty common, I try to stick to the ellipsis for example… I have to say that the compose position for dieresis is a bit more logical (compose-" as opposed to macs alt-u), which is quite useful if I don't want to switch keyboard layouts when typing a bit of German (or write a lot about Motörhead and Queensrÿche).
X11 also has "level 3" support, which is straight-forward additional characters when pressing a certain key, as opposed to combining multiple key presses. Mac's alt key basically does both to a certain degree. The fact that it's turned on by default and the keyboard viewer makes it a lot more common usage in my experience.
1. Change your layout from "USA" to "USA International (AltGr dead keys)". Then use right-alt+key to make various special characters (you can look at what each character does at "Show Current Layout").
2. Enable the "compose key" -- I use the Menu key for this -- which is described at http://sivers.org/compose-key (it's simple to enable: Keyboard Preferences→Layouts→Options→Compose Key Position). Both of these are customizable, so you can add your own combinations if you want.
There are some other ways:
3. Ctrl-Shift-U in a GTK+ text input to enter a code point, as you said.
4. Alternative input methods that let you type special characters in in various other ways, such as LaTeX names, if you prefer that.
A lot of key emacs bindings--C-a, C-e, C-n, C-p, C-f, C-b--work in any text field (even, say, the Hacker News comment box). But M-f and M-b (which are really useful since they get you forward/backwards a word instead of just a letter or a whole line) don't work. When I try to type option and then a letter, I get weird symbols:
Here's option-b: ∫
Here's option-f: ƒ
To get make M-f and M-b work, go to Preferences->Settings->Keyboard and check the "Use option as meta key" box.
See http://skitch.com/jackowayed/dme91/terminal-fix-keybindings if you can't find it.