Mac OS X: FastScripts is a lightweight microapp that makes it really easy to access you AppleScripts from your Mac menubar. It provides you with access to scripts in multiple locations and let you assign keyboard shortcuts for super fast access.
FastScripts automatically finds the scripts already in your Mac OS X library folder so there's really no setup required. In addition to letting you quickly run any of your scripts, you can easily edit them as well by holding down shift and selecting them from the menu. If you use a lot of AppleScripts and want quick access through your menubar and keyboard, FastScripts is a really great tool for the job.
FastScripts is kind of expensive ($US15) if you buy the full version, but the free lite version lets you use the menubar fully and assign up to 10 keyboard shortcuts to your scripts. If you're not going to assign a crazy amount of keyboard shortcuts, that should be more than enough.