Reversing a file line-by-line seems not very interesting, but may be in fact very helpful in a lot of cases, especially under Unix-like systems.
Interestingly, just after reading a very good article on that particular subject from the printed edition of the Sys Admin Magazine, great known NetBSD developer Hubert Feyrer blogged about this issue... growing the proposed solution with a new method not yet given, although very simple.
All the spirit of UNIX can be found here: combined different powerful general tools to achieve a very specific task... sounds great to me.