OS X.5 / X.6 - Create Sparseimage:
Open up terminal and type:
hdiutil create -size 10g -type SPARSE -fs HFS+ -volname vname iname
10g → max. size of the sparseimage
vname → name of the volume
iname → name of the image

All howtos are without any warranty.
Alle Howtos sind ohne jegliche Gewähr oder Garantie.