One area sadly lacking in most Linux installs is the availability of really nice fonts useful for design and great fonts are not cheap, circa $150 for a font set. Best all in one location for getting great free fonts, I think is www.fawnt.com
If Ubuntu really wants to have a go at competing with the Mac, this is certainly an area that needs improving.
You can install fonts system wide by dropping them (or folders of font families) into /usr/share/fonts or alternatively, kfontviewer a KDE application will give you a nice gui for installing fonts.
Need to manage large amounts of fonts on Linux? Try Fontmatrix
sudo apt-get install fontmatrix