The character palette is also available under Edit->Special Characters in most applications, or by the shortcut Cmd-Opt-T (or ⌥⌘T if you will).

Under Linux you can enable the compose key, with setxkbmap -option "compose:rwin"

This lets you prefix digraphs with rwin, and have them print unicode characters. This is (to some extent) configurable, although I am not sure on the location of the mapping.

EDIT: Some examples (default settings): ä ç ß ¢ £ ½ ⅓ ¼ ⅙ ⅛ » « ¥ õ ° — – º

Nope, just little blocks. Some interfaces display it as one solid dark monolith, some as empty squares, and a special few as festive little glyphs with mysterious markings inside. (XP SP2, every browser under the sun and then some.)

With OS X you take beautiful fonts for granted sometimes...

You probably just need to track down the right font that has them.

Sure, because everyone wants to have to mess with their global font settings in order to use a website properly

Probably true, but it shouldn't be that difficult to set up a unicode font as a fallback for all other fonts.

I see them fine on Ubuntu/Firefox

in windows xp with google chrome I just see box box box box box etc. In fact nothing on the blog displayed either.