I've covered almost all passwords by issuing the command 'service password-encryption'
However, there is still one key that I am still able to see when I do "show run" and that is the pre-shared key that my router uses to establish an IPSec tunnel.
What is the command to hide this key?
I'm glad that worked for you. Here are a few links that discuss the command:
Depending on what software version you are running on the router, you can use the 'key config-key password-encrypt ' command (requires IOS 12.3(2)T or later). Here is a link to the documentation for this feature:
Hope that helps.