How do I mount an ISO?

If you prefer to keep it old school, in a terminal:

sudo mount /path/to/iso /path/to/mountpoint -o loop

This, of course, will not allow you to edit the ISO as the other mentioned tools will, but if you just need to quickly get into one and pull a few files from it, works like a charm :-)

Brasero which comes with Ubuntu is able to create and open (to manipulate) ISOs. If you're looking for a way to mount an ISO so it's contents are available like a "drive" you may want to use simply Right Click the ISO and choose "Open With Archive Mounter" which will mount the ISO as a drive and you should see it listed under the Places menu.

This all assumes you are using 10.04

I always used Gmount-iso to mount ISO files.

apt-get install -y gmountiso