[Princeton]

ALT is used for alternate text (if image viewing is disabled in application show alternate text).

Many people confuse the ALT attribute with the TITLE attribute -- TITLE will produce a tooltip. NOTE: IE displays the ALT as a tooltip but that was done because of compatibility issues with early Netscape browsers. This is not the correct way of using the ALT attribute.

Another way to look at it:
ALT values are parsed by search engines while TITLE values are ignored.
So, if you have many icons on the page with NOTEPAD (alternate text on notepad icon) you are actually hurting your SEO.

you should just leave the ALT empty - as the icon seldom has nothing to do with the message

For example:
{Notepad} Star Trek MMO Exclusive Interview