This search utility supports Perl regular expressions (".?" will match a single character, ".*" will match any length of characters). The Search is not case sensitive (ie. if you say "kzin", it will match "KZIN", "kZin", etc). For a more thorough explanation of regular expressions in Perl, see Programming Perl by Larry Wall and Randal L Schwartz, or the online perlre - Perl regular expressions document. Note, that html/http don't transfer all of the meta characters intact, so you might want to just stick with simple use of the above two patterns.
An example of using the above patterns:
if you wanted to match all nicknames that contain "k", you'd use this:
If you wanted to match any nickname that was exactly 1 character long,
If you want to list the home pages of every nickname on this system: