Really depends on what you want.
You could use linked files. To do so simply have one "common" project with the resources and in the second project you use "Add Existing Item", before you click add, click the small arrow right to the button and say "linked file". This will not copy the file but keeps it in the current location. But it will treed it as if it is a normal project file...
If you just need static content shared across multiple web sites,
a) have one web site storing the static content and reference all URLs to link to that static content web site.
b) If you don't want to host a separated web site for the static content, simply create a sub website within each main web site...
If you have static content, create a virtual directory within your web site linking to a folder with all your static content.