You can make popups
without caption.
Or you can make them have a
caption.
You can also make them appear on the
left,
and of course use a
caption.
You can also make a
sticky
that stays put when you click on it. It can contain any html you wish.
Of course you can also make ones that show on the
left.
To really know how useful these can be you should check out the site
I made these for,
The Visual IRC Guide.