PlugSuit Installer

PlugSuit is a manager and loader for extenders, little programs that add functionality to your applications.

It powers ∞labs's Afloat, and also works with most other SIMBL and InputManager extenders.
PlugSuit doesn't just reinvent the wheel — it provides useful extras such as an easy-to-use System Preferences pane to manage your extenders (or turn them off altogether!) and a few niceties such as update notifications for compatible extenders.