Most players who spend a lot of time raising their professions, whether it is for interests in making gold, crafting themselves some neat gear pieces, or just for the fun of doing so, do it with a passion. If you can recognize yourself from that description, I suggest you have this addon ago.
The addon provides a nice way to help you list recipes and designs that you yet do not possess, making them easier to acquire and thus widen your field of expertise. The way it works is you open your profession window and simply hit a button. The addon then scans your recipes and provides a window of its own, listing the ones you do not yet possess. Further more, it also lets you know where to get the particular recipe, from vendors to world drops, showing in both name and map coordinates.
I used to do this by reading thottbot and wowwiki, going through long lists or recipes, locating vendors, etc. but this has been my salvation. It's quick, easy and I can actually concentrate on getting the recipes rather than locating where and if something exists.