xfburn is easy to use burning software for the Xfce desktop environment (but will work with others). It uses libburn and libisofs as a backend. ISO files can be burned, data composition created, discs blanked, and DVD-RW media formatted and deformatted. Common burning software features not yet implemented are audio CD creation and disc copying.
SvOlli's Little Audio Related Thingies, or SLART for short, is a compilation of rather simple programs that are related to audio files: it consists of a player (Partyman), a CD ripper, a tag editor, and some other tools. These programs can communicate with each other via a custom IPC bus, so a newly ripped track can be automatically queued in the player, for example.
cdrkit is CD Recording Kit, a collection of applications related to creation of optical disk media on Unix platforms, from creation of the filesystems used on such media to the actual burning process. It is heavily based on the cdrtools package (partially developed and maintained by Joerg Schilling before), but is maintained independently.
RipOff is a GTK+ based CD ripper for Linux (and hopefully for other Unix systems once some testing and fixing have been done) that has a simple interface, CDDB lookups, and a plugin-based encoder architecture. It attempts to appeal to those users who want a non-GNOME dependent CD ripper with a simple interface, or users who just don't like the interfaces of the other GTK+ CD rippers.