When I first asked how to achieve something like this: http://backpack.tf/ I got pointed to JQuery.
I managed to create a new small window when I hover over images using this; http://jqueryui.com/tooltip/
But I can't figure out how to construct it so that it can show detailed information about some PHP object like in backpack.tf
Is JQuery the correct way?
Use JQuery Power Tip
http://stevenbenner.github.io/jquery-powertip/
you just need to put your html in element title attribute.