A plain popup,
or perhaps one with a caption.
You can also make them stick when you click,
plus, you can place any html you wish in them.
There is lots more you can do like placing them on the other side of the mouse,
snapping to a grid,
fixating the position,
Making the popup go above the cursor to the left with snap!
Taking full control over the html
Different fonts and colors
Background picture with transparency