I have a custom content type that has a custom field called "stock."
I would like to have a single page that shows me all "stock" values in a list, and allows me to change the value. Is this possible?
Create a view filtered on your content type and include a "NODE: EDIT LINK" in the FIELDS along with all the rest. You can then click on that to edit the node. Anything fancier requires digging into views tpls and custom node edit code.
Create a view with the content type and the field you wish to edit, then use Editablefields module to let you edit them inline.