Let's say you want to create a Views block that shows on a bunch of different pages/nodes that have multiple (imagefield) images per page, and you want the block to dynamically display ONLY the images from the particular node you're on--and not display images from other nodes.
This is how you would do it:
1. Create your view as you normally would.
2. Add "Node: Nid" under "Arguments".
3. Select "Provide Default Argument" under "Action to take if argument is not present:"
4. Select "Node ID from URL" under "Default argument type:"
5. Leave everything else as is...
6. Hit "Update" and then "Save"... and you're done.