Images for several Kubuntu flavours are available.

1. Kubuntu 6.06.1 codename Dapper Drake
   Size (compressed/uncompressed): 420.4 MBytes / 2.11 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/kubuntu-6.06.1-x86.7z
   Active user account(s) (username/password): ubuntu/reverse
   Notes: from standard ISO image, Guest Additions not installed (HOWTO)
2. Kubuntu 7.10 codename Gutsy Gibbon
   Size (compressed/uncompressed): 512.4 MBytes / 2.7 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/Kubuntu-7.10-x86.7z
   Active user account(s) (username/password): ubuntu/reverse
   Notes: from standard ISO image, Guest Additions not installed (HOWTO)
3. Kubuntu 8.04 codename Hardy Heron
   Size (compressed/uncompressed): 515.5 MBytes / 2.27 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/kubuntu-8.04-x86-kde4remix.7z
   Active user account(s) (username/password): kubuntu/kubuntu
   Notes: with KDE4 Desktop Environment, from standard ISO image, Guest Additions not installed (HOWTO)
4. Kubuntu 8.10 codename Intrepid Ibex
   Size (compressed/uncompressed): 463.1 MBytes / 2.49 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/kubuntu-8.10-x86.7z
   Active user account(s) (username/password): kubuntu/reverse
   Notes: with KDE4 Desktop Environment, from standard ISO image, Guest Additions not installed (HOWTO)
5. Kubuntu 9.04 codename Jaunty Jackalope
   Size (compressed/uncompressed): 539.4 MBytes / 2.55 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/kubuntu-9.04-x86.7z
   Active user account(s) (username/password): kubuntu/reverse
   Notes: with KDE4 Desktop Environment, from standard ISO image, Guest Additions not installed (HOWTO)
6. Kubuntu 9.10 codename Karmic Koala
   Size (compressed/uncompressed): 488.0 MBytes / 2.3 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/Kubuntu-9.10-i386.7z
   Active user account(s) (username/password): virtualbox/virtualbox
   Notes: with KDE4 Desktop Environment, from standard ISO image, Guest Additions not installed (HOWTO)