On Ubuntu Gutsy, if you have installed KDE 4.0, as per this page on Kubuntu.org, you might notice that in Gnome , your Skype font is much too large.
The solution is to
sudo apt-get qt4-qtconfig
then, from the terminal , type
/usr/bin/qtconfig-qt4
You will notice that the QT window has fonts about the same size as the big Skype ones. Change them using the QT Config interface, select File -> Save.
Your Skype fonts will then be back to something more normal in Gnome.