This is a list of commands that I use but always seem to forget:
Find an unused loop-device
Display all used loop-device
Disassociate an existing loop-device
To mount the disk image, First identify the loop-device you would like to use. Then associate it to the file name. If you have an auto-mounter configure the device may be automatically mounted, otherwise you will have to manually mount it with the "mount" command using the loop-back device
You can usually perform the association and the mount in the one operation
For me, on Ubuntu 9.04 the Network manager applet dies every now and then. Especially when editing/deleting wireless configurations.
To restart it do the following.
If you don't have audio in youtube the following will probably resolve it (on Ubuntu 8.04)
ddrescue in package gddrescue (the 'g' is for gnu, not gnome)
This will print three lines per attached apple device: The manufacturer, the device name and the UDID (called “iSerial”).