Fill blank image TITLE attributes with what's in their ALT attribute, if found.
When you're on a page that has ALT attributes set on images but no TITLE attributes, you won't see the tooltip text when hovering over the image. Alt-Titler fixes this, by copying the ALT attribute contents into the TITLE attribute, if there's nothing already in the TITLE attribute.
Alt-Titler is especially useful on Twitter which has just surfaced the ability to add accessibility descriptions on images but is only showing those descriptions in ALT attributes, which don't show on hover.
Please hold your lectures about how ALTs are not TITLEs, and that I'm breaking all kinds of HTML standards and intentions. I know. All I want to do with Alt-Titler is to give those descriptions a wider audience.