Link List That Controls Another Web Part
Add two Content Editor Web Parts to the web part page.
In Web Part A add the following code:
<iframe name=”myframe” src=”http://www.msn.com”></iframe>
In Web Part B add the following code:
<li><a href=”http://www.microsoft.com” target=”myframe”>Microsoft</a>
<li><a href=”http://www.msn.com” target=”myframe”>MSN</a>
<li><a href=”http://msdn.microsoft.com” target=”myframe”>MSDN</a>
The net effect is that clicking a link in Web Part B causes it to display inside web part A.
If you want to get fancy, you can use a data view web part to render Web Part A from a list based on the Links list template, and modify the XSL to target the frame in Web Part B.