Zapping is a television viewer program for GNOME. It's fairly similiar to the xawtv package in general, but has some cool features that make it special.
First, it supports both Video4Linux and V4L2, which is an entirely different, newer and more capable API. I'm not sure if xawtv can do that just yet.
Moreover, Zapping has everything integrated into a nice GUI (however, I'm not saying xawtv's UI would be much worse). For example, there's no need to use xawtv and AleVT separately, Zapping has an integrated teletext browser (called Zapzilla). It also supports teletext subtitles (for example, in Finnish channels, some programs are subtitled for hard-of-hearing people on teletext page 333).
Also, Zapping supports plugins. You can write plugins that do strange things to the image, for example, save the program to the disk in some format, do some transforms, or make plugins for different controllers (LIRC support is there).