Fontilus in action on a work PC:
[image|http://guildenstern.dyndns.org/pics/tech/screenies/fontilus.png||Fontilus window and font details pane||]
Fontilus is an extension to the Nautilus file manager that gives you drag and drop font management.
Yes, you can drag new fonts into that window and install them.
A minor nit I have is that the font preview panel doesn't seem to respect my desktop font hinting preferences. This is more than offset by the little bit of history that some fonts have embedded.