Here are applications that are known to work with UML:

ApplicationVersionReported by Notes
Apache 1.3.22 WLS
Bash 2.05 WLS
Bind 9.2.1 WLS
Bitkeeper 2.1.6-pre5JD
Half-life server4.1.1.0WLS
Imap/ipop 2001a WLS
Mod_perl 1.27 BT
MySQL 11.18 BT
Openssh 3.3p1 WLS
P0f 1.8.1 WLS
Pine 4.44 WLS
Rsync 2.5.4 EW
Sendmail 8.11.6 WLS
Squid 2.4.STABLE6WLS
Tomcat JD Needs kernel >= 2.4.19-35um
UML itself JD UML can actually run inside itself.
Wu-ftpd 2.6.1 WLS
xntp 5.93 WLS