apt-get - list of software?

[welly]

Hi all,

Question regarding apt-get. I understand it's the command line alternative to Synaptic, and I've noticed that people have recommended its use. However! Should I want XYZ application downloaded and installed, how would I know what name to use with apt-get? Is there an apt-get --list or something similar? Is there a page anywhere which lists all the software available using apt-get? I wanted to get hold of mplayer which a few people have recommended so tried apt-get install mplayer. Didn't work unfortunately. Basically how do I know the name of the package to use with apt-get for any application, not necessarily mplayer?

Cheers!

Welly