As Kuros said, Photek 8.1 is a great compilation of add-ons that will completely overhaul and customize your UI. If you go into the screenshot thread you will see a screen of what it looks like similar to what it looks like now, although it has changed since a recent major patch came through.
http://wow-en.curse-gaming.com/downloads/details/3459/ That is Photek 8.1
Other add-ons that I use that aren’t found in Photek are Auctioneer, Gatherer, Gatherer-Sync, Atlas, and AtlasLoot. Auctioneer will keep track of all your auctions basically in the auctionhouse. You can scan the AH and it will generate an average price so that when you put the same object up in the AH, it will put the prices in for you and it makes things really simple. Get the auctioneer pack from http://www.auctioneeraddon.com , all of the addons that come in the pack will add a bunch of useful stuff, such as telling you how much white/grey items sell to the vendor or even BoP items that you can’t use or don’t want anymore. Gatherer will keep track of all of the things you pick up for your professions, such as any herbs or mines you mine. Also, if anyone in the guild who is using gatherer gets an item then it is automatically sent to you as well so that it adds it to your map. Gatherer-sync allows people to share their entire data packet with you so that you can get their maps and find herb/mines/etc a lot easier. Atlas is just another map add-on that will display entire dungeon maps as well as locations for world dragons, etc. Atlasloot allows you to link and see the loot that bosses in instances, etc drop as well as link the loot if it has been seen on the server.