FuBar is a panel mod, similar to Titan Panel. FuBar has many shiny features and shoots for low memory/CPU usage.

Features:
Drag and drop rearragement of plugins.
Any plugin can exist on left or right.
Automatically adjust frames (can be turned off)
Any number of bars (not limited to just 2), you can attach to the top, bottom, or detach any amount you want.
Can detach a tooltip and pin it to the UI.
Object-oriented design.
LoadOnDemand capabilities for plugins.
Modularity (absolutely no plugins are intimitely connected to the core)
Minimal resource usage
Lots of handy features for developers.
Well documented API. (see API.html)
Skinning support
Can change the thickness, font size, transparency, spacing through simple sliders on the right-click menu.
Can place plugins on the minimap, which will function like standard minimap buttons.