Here is an AWESOME gruhabhedam demonstrated by Prince Rama Varma:
http://www.youtube.com/watch?v=Nnq5tdukBeg
Once the concept of gruhabhedam is clear, doing it with linear (monotonic) ragas is fairly straightforward- say between Mohanam and Hindolam. But here, its two vakra ragas (i.e. with scales where swaras don't exactly monotonically increase or decrease) which is what makes it so special! The "pa ma2 pa ga3 ma1 ga3" phrase of Behag mapped to "ga2 ri2 ga2 sa ri1 sa" of Sindhubhairavi was so revealing!
What's more, the inflections (or "brighas"/ "gamakams") of the swaras match too!
Music is beautiful. Math is beautiful. And the two put together- ah, bliss!
For those interested, here's an earlier post of mine where I'd explained the concept of Gruhabhedam (albeit overly simplified)-
http://octaves.blogspot.com/2007/06/carnatic-chills.html
(Note: It was only later that I learnt from Shri.Kumaresh (of Ganesh-Kumaresh) that the word "Shruthibhedam" for such transposes is a misnomer, for it only means what it literally means: change of shruthi, and nothing more)