I run PowerPro as a launch bar. Since PP does a gajillion other things I don't use/want/need a lighter launch thingie that is similarly configurable would be great. Some things mentioned that PowerPro can do that a replacement would ideally do:
Sit in system tray and popup a menu.
Hide at an edge and show (bar, menu, whatever) when edge is hit.
Use multiple methods for launching- shortcut buttons, menus, hotkeys, ?...
Group shortcuts or menu items visually by selectable criteria: category, type, alphabetical, whatever.
I have my PowerPro bar set up much like the launch panel from
XFCE( a linux window manager app ) where there are icons which represent my most-used app in that category and are activated by a left-click. Right-click on the same icon gets me a menu of other apps in that category. For example, my Firefox button of course opens Firefox when I click it. A right-click pops up a menu of the category "internet" that includes IE, Filezilla, Opera, and may also include Instant Message and IRC apps, Upload links, etc.
Two cents and all that.