Eucalyptus wiki includes links to several sample VMs/kernels/ramdisks.

For the convenience the steps required to download, package and upload sample VM are listed below.

OS in question: debian 5.0

 # get the archive
 wget http://www.eucalyptussoftware.com/downloads/eucalyptus-images/euca-debian-5.0-x86_64.tar.gz 
 # unpack
 tar xvfz euca-debian-5.0-x86_64.tar.gz
 # make sure you have  ec2 tools in your path and working credentials. To test, execute e.g. ec2-describe-availability-zones.
 cd euca-debian-5.0-x86_64
 # package kernel (kvm)
 ec2-bundle-image -i kvm-kernel/vmlinuz-2.6.28-11-generic --kernel true
 ec2-upload-bundle -b debian-5.0-x86_64-kvm-kernel -m /tmp/vmlinuz-2.6.28-11-generic.manifest.xml
 ec2-register debian-5.0-x86_64-kvm-kernel/vmlinuz-2.6.28-11-generic.manifest.xml
 # now ramdisk
 ec2-bundle-image -i kvm-kernel/initrd.img-2.6.28-11-generic --ramdisk true
 ec2-upload-bundle -b debian-5.0-x86_64-kvm-ramdisk -m /tmp/initrd.img-2.6.28-11-generic.manifest.xml
 ec2-register debian-5.0-x86_64-kvm-ramdisk/initrd.img-2.6.28-11-generic.manifest.xml
 # and finally disk image binding default kernel and ramdisk to that, put kernel/ramdisk IDs there
 ec2-bundle-image -i debian.5-0.x86-64.img --kernel eki-<KERNELID> --ramdisk eri-<RAMDISKID>
 ec2-upload-bundle -b debian-5.0-x86_64-kvm -m /tmp/debian.5-0.x86-64.img.manifest.xml
 ec2-register debian-5.0-x86_64-kvm/debian.5-0.x86-64.img.manifest.xml
 # Voila! test out that images are correct:
 ec2-describe-images

NB! Running that image with default vm type (m1.small) will fail as the image needs more diskspace.