Question : I have a TON of documents that I know I have permission to! Why can't I put them on a page?
Answer: While you may have access to see the documents, the Workgroup may not have access to display them. (And this goes both ways- a Workgroup may have access to display the document but the viewer must also have access to the document in order to view it as well. MOST groups have the Employee Role set up to read documents... but make sure your's does or you may run into more issues! Sensitive documents likely have special permissions in place which means they won't be readable to the general Employee Role).
So - let's run through how to give a Workgroup permissions...
In order to link those list islands on your workgroup pages, you'll need to give that workgroup access to the directory itself.
Here are a few screen shots that'll walk you through that process:
Go to Portal Tools > Manage Portal Documents > Manage folders
Find the folder in question, click the drop down, and press "edit"
Add the name of the work group where you want the list island to display and add it to the right side column and save. (The green ones are work group names).
*If you're going to eventually MOVE the page (i.e. building it "backstage") then give THAT workgroup permissions too. Think forward so you don't find yourself stuck trying to figure this out again in the future. If the Workgroup that you're building this page for already exists, you may as well assign permission to that Workgroup now to save yourself the hassle and confusion later.
Once you've done that, you should find it on your work group list island.
A big shout-out to Adam at Excite for this fabulous quesiton!