How to allow Anonymous Access to one list (e.g. a picture library) in your SharePoint 2007 site

It is a 3 stage process to enable anonymous access to a specific list in your site (and only that list, not the rest of the site). This is particularly handy if you want to allow users to see images (via the html img tag) in MOSS-generated workflow emails - but don't want to make the whole site public. This is really the equivalent of an unauthenticated /Images directory in an ASP.NET web app).

If you follow the instructions from this article from MSDN under the heading "Enable anonymous access for individual lists", you will realise that the steps under that heading don't work by themselves. That is, you have to perform all steps listed for enabing anonymous access in the site collection and site level before you can enable anonymous access for lists:
http://technet.microsoft.com/en-us/library/cc263363.aspx#Section4.

To enable anonymous access to a particular list on your site, you need to do the following (in this order):

1. Enable Anonymous access for your site collection through Central Admin->Application Management->Authentication Providers->Default-> Check On Anonymous Access
2. Enable Anonymous access for the site through Site Actions->Site Settings->Site Permissions->Settings->Check on Anonymous Access
3. Enable Anonymous access on the list you want available to anonymous users e.g. Site Actions->Site Settings->Site Administration-> Site Libraries and Lists->Click Customize PictureLibrary->Permissions for this picture Library->Settings->Anonymous Access-> Check On the 'View' checkbox.

Note that if you do 2 before 3, you will be presented with a list with all the options greyed out (i.e. you cannot check on "View" permission for anonymous users.)