This should probably go to the UI forums, but you can get Grid at
www.wowace.com
This is what Grid looks like (standard, you can make it look very different): each person is represented by a square. Information pictured on a square is fully customizable, usual set up is class color coded name on black background in the middle (first 4 letters). The black background is actually inverted healthbar - it fills up as the person looses more and more health. The name text is usually switched for hp deficit number once the person lost certain % of hp (you cet up all the thresholds etc). You can set up indicators at the corners of the square and customize what the indicators are responsible for (there are addons on top of Grid that add indicators to the sides of the square as well). You can set up these indicators to show a ton of stuff - any HoTs, any debuffs you can cleanse, wether they have agro of a mob, their pvp flag etc. You can mark debuffs by group or look for a specific debuff. You can set up an indicator to watch for a specific debuff like "Web Wrap" was very useful for identifying people on the wall at Maexxna.
There's pics and its own forums at wowace.com as well. Setting up Grid the way you want it is a daunting task and would take you a couple of hours in itself.