letter-spacing
This property sets the amount of spacing between letters. Values can be set in various units (negative values are permitted) or to the default value normal. Because you can't cross tags, you may not have full control over inter-character spacing; in other words, the letter-spacing property should not be confused with the ability to fully kern text.
Example
.tight {font-family: Arial; font-size: 14pt; letter-spacing: 2pt;}
p {letter-spacing: 1em;}
p.norm {letter-spacing: normal;}
Browser and CSS Support Notes
CSS1
IE 4, 5, 5.5, 6
Nav 6, 7
Opera 4, 5, 6, 7