XChar allows you to quickly use uncommon characters even if you don't remember the key combination you need to use a certain character. How? XChar displays a window containing all the characters that your Mac can display. When you need one of it, simply drag and drop it on the place where you need it. And when you don't need XChar, you can reduce its window to a small icon and place it where you want on your screen. When you'll need it again, simply click on it and it will zoom again. Moreover, XChar is a standalone application and doesn't need any special extension to run.
What's new in XChar
Version 3.0.1 adds the following:
Better character display in the XChar palette
Now miniature window is repositionable under Mac OS X too.
Now Smooth resizing works on Mac OS X 10.2.x too.
ixed a bug that made XChar window disappear when monitor configuration changed
I won't say this program is bad, but PickChar performs the same functions from a menu bar icon and is free (but does not support Drag&Drop, like this one). Both do not handle Unicode, so their value is limited.