http://packages.vmware.com/tools/index.html

Resizing a disk only
vmware-vdiskmanager -x 4Gb CentOS5.vmdk

Merging snapshots and reducing disk
vmware-vdiskmanager -r Windows_XP_Pro-000001.vmdk -t2 -s 6.0Gb Windows_XP_Pro_dest.vmdk
then choose the new image in the virtual machine config and get rid of old ones