Since there are still people having troubles with finding servers in the serverbrowser I'll post a short fix. These fixes work for all platforms and they aren't bugged like the official HumanHead fix. I highly suggest to use this fix instead.
Any version, make sure the game isn't running! 1) Go to your installationfolder and find the /System folder 2) Open your Rune.ini file with a texteditor such as Notepad 3) Find (CTRL+F) each line that includes master.gamespy.com or master0.gamespy.com and replace it with master.333networks.com. By default there should be 3 lines that need to be replaced. 4) Start up the game