So anyone who has been around the mod scene for a while has probably heard of a little mod called PowerAuras. It's a great little tool that pops up visual indications of pretty much anything you want. In fact it functions a lot like a customizable version of the many proc indicators that are now in the base game, and was most likely where the inspiration for these indicators came from.

Anyways I just heard about a little addon by the name of WeakAuras. Apparently it was originally designed to be a replacement for PowerAuras, but apparently by this point it incorporates things that PowerAuras does not, in addition to being more lightweight and easier to use.

I've not tried it out yet but from what I have heard, and a glance at the addon page, it looks promising. Definitely going to give it a whirl.

http://wow.curse.com/downloads/wow-addons/details/weakauras.aspx