Recently i was reading the blog post Public-Facing SharePoint? Here's something scary... Please activate ViewFormPagesLockDown!!! and i want to highlight one piece of information when you activate ViewFormPagesLockDown feature (can be activated only through stsadm) you are securing all the pages inherit from LayoutsPageBase, so if you want to add your own pages to be still accessible let them inherit from UnsecuredLayoutsPageBase

MSDN documentation for UnsecuredLayoutsPageBase

In general, use UnsecuredLayoutsPageBase as a base class for pages to which even unauthenticated users must have access; such as a login page.

For a page base control to which access can be limited to users that possess certain rights, use LayoutsPageBase.

Typically, you create a class in a code behind (.aspx.cs) file that derives from UnsecuredLayoutsPageBase. Your .aspx file, in turn, inherits from your custom page class. For example, the c:\Program Files\Microsoft Shared\web server extenstions\12\TEMPLATE\LAYOUTS\login.aspx page that ships with Windows SharePoint Services 3.0 inherits from an internal class named LoginPage which itself inherits from UnsecuredLayoutsPageBase.