It would be helpful to be able to specify an image as the "title" of a widget, instead of being forced to use text or not specify a title and then have to include the image in the body of the widget instead. For sites with a lot of content in the sidebar, it really helps add visual appeal if you're not just using a bunch of text.
As it stands now, if I forgo a text title and include an image in the body of a widget to act as a faux title, when I look in my Dashboard I see a slew of widgets that just say "Text"--telling me nothing about which widget is which until I open them to see.
I would like to have something added to the widgets interface where I should specify an image as the title, and in the Dashboard I could either see the image or a smaller version of it as the title so I know which is which at a glance.
Barring that, it would be nice if we could specify "hidden" titles for widgets that would only be visible in the Dashboard. That way, if we're forced to place title images within the body of widgets, we could at least use the "hidden" title to tell them apart easily.