EDIT

Since v2.0 this addon no longer uses the default Raid UI, the reason is simple, it's not useable anymore since wow client 4.3.1. we had no way to maintain a raid frame in the secure way while itself wasn't entirely written in secure codes. So I decided to create my own buttons instead, this offers more flexibility and combat safety, at least the UI no longer mess up when ppl join/leave your raid during combat. So you may treat the old description below as a history, just to show the original motivation of develop for this addon.

END OF EDIT

I'm not sure how many people have paid real attention on the new raid frame UI came with WOW 4.0 (Cataclysm), if you looked into the source code you would probably find out how much efforts Blizzard UI folks had dedicated in, and how sad it turned out that no one even wanted to touch it. The reasons are apparent: ugly looking, lack of important utilities, and most important, there are a few superior addons out there doing fine for years.

Having said that, being a Blizzard UI, it actually offers some special advantage that other addons never will. For example, it is not restricted by the secure framework so you can manually show/hide raid groups or change unit frame sizes during combat; It is a built-in addon, most of its templates and UI objects are already created before any third-party addons are loaded, use it or not, game resources are occupied regardlessly. If some day this Blizzard's raid UI suddenly turns into something that looks as fashional as whatever you can imagine, and has all advanced features you ever wanted, would you consider giving it a try? Now you probably are going to ask: "Can it?"

CompactRaid is an addon that simply answers "Yes" to your question, it greatly improves the Blizzard's default raid frame UI to make it become compatitive with, if not better than, any other third-party raid frame UI. It currently consists of the following working modules:

Modules integrated in CompactRaid

Core module: Wraps all internal framework, provides exported API's for other modules.
Artwork module: Enhances the UI lookings, supports LibSharedMedia-3.0, LibSharedMedia-2.0, CWDGMediaPack, you can choose text fonts, status bar textures and background arts from those libraries and apply them to your unit frames.
Corner Indicators module: Adds indicators to corners of your unit frames to help you tracking configured auras, supported displaying modes: icons, color dots, numeric texts.
Raid Debuff module: Displays bold icons on unit frames to alert critical raid debuffs. Requires raid debuff data module, for current version it's "Cataclysm".
ClickSets module: Binds mouse clicks on unit frames to help you quickly cast spells on hovering unit. Supports mouse wheel.