PylotLight is a cross-platform, themeable, plugin-supporting system for general computing tasks. It is comparable to QuickSilver, which you may recognize if you use a Mac. Current plugins exist for Web searches, Firefox bookmark launching, filesystem browsing and managing, subversion control, terminal control, and more.
ISOmorphin is an ISO mounting manager for GNOME. It can mount/unmount, with a list of ISOs that can be mounted, and mount DVD ISOs with autoplay in you favorite player. There is no need to have root access for mounting (mount is done via FuseIso, so ISO, BIN, NRG, IMG, and MDF are supported). Conversion from extra image formats to ISO and ISO creation from files or media are supported.