GNOME Do allows you to quickly search for many items present in your GNOME desktop environment (applications, Evolution contacts, Firefox bookmarks, files, artists and albums in Rhythmbox, Pidgin buddies) and perform commonly used actions on those objects (Run, Open, Email, Chat, Play, etc.).
RRD is the acronym for Round Robin Database. It is a system to store and display time-series data (i.e. network bandwidth, machine-room temperature, server load average).