Change default logo

As the owner of a wiki you can modify the logo that appears at the top right of your wiki by following these steps

Create an image no wider than 150 pixels and no taller than 200 pixels in either GIF, JPEG or PNG format and then E-Mail Matt Clare with your request and the file.
Upload the image to the internet. You can even upload the image to your own wiki, but you may want to protect it.
Copy the URL for the image.
With the account you used to create the wiki, login to the Modify the settings of an existing wiki area.
Navigate to the Wiki Settings page
Paste the URL into the Logo URL: field and press Modify.
Verify that the new log appears both in the settings list and on your wiki.