Sreedhar,
Unfortunately, I can't recommend much in the way of GOOD GPIB applications, as I am wholly unsatisfied with the quality of National Instruments' instrument drivers for various instruments (with regards to style). However; instrument drivers are going to be your best bet for examples. Try the instrument driver CD that comes with LabVIEW, or download some from the NI website.
GPIB is merely a form of communication. As such, the applications should be very simple.
Hopefull that helps.