1. Rearrange the interface, use a smaller font allow for more than a small amount of browsers to be displayed.
Perhaps some cosmetic changes (or a complete overhaul) would be nice. The font support is non-existent though, so the smaller it gets, the crappier it looks. It might be possible to fit another server in the list without it looking too terrible.
If you have specific suggestions or mockups for improving the interface, suggest away.
2. Change the default sort to Player Count descending
That would typically mean that the servers with the highest maximum number of players would be listed first. That is probably not a good idea.
3. Force server ops to "register" with the master server. Allow the master-server the ability to reject nonsensical server-names that are only used to exploit the default sort.
Your server automatically "registers" with the master server when you host an Internet game (dedicated = 2). In svn, not only are servers sorted by ping, but sort by name ignores non-alphanumeric characters. Making the master server do extra work to work around a non-critical client bug that has since been fixed is dumb.