The BiLE suite includes a number of PERL scripts that can be used by a Penetration Tester to aid in the enumeration phase of a test. BiLE itself stands for Bi-directional Link Extraction utilities. The suite of tools essentially can be used in the footprinting process to find both obvious and non-obvious relationships between disparate. With this information a Pen Tester may then decide to try and access sites with close realtionships to the target as a means of a stepping stone into the target network.
Note: - This process depends on the fact that the linked sites you plan to attack to get thru to your target are actually owned by the target company and are in the scope of the test.