Apart from the collaboration with Citibank PremierMiles to offer 10 PremierMiles/Rs. 100 for travel reservations made via Yatra.com, Yatra also has another promotion ongoing for Citibank credit card holders, for cards issued in India.
For the month of April 2013, the first 500 travel reservations made everyday on Yatra.com and paid for with a Citibank credit card (issued in India), can use promotion code CITIYAT and take Rs. 1300 off their reservation. If you are not one of the first 500, you still get Rs. 250 off for one-way flight bookings, Rs. 500 off for return flights and Rs. 500 off on hotel reservations. And not just once, this code is valid four times per card, which means if you can catch the discount, you can get up to Rs. 5,200 off in your reservations with Yatra.com.
If you were booking flight reservations, for instance, you could break it up into individual passengers and individual flight legs and take the maximum discount off the table, since this is the best discount I know of at this moment on the various travel portals.
The day resets everyday at 00:00 IST so the best chances to book your tickets and get a discount are early in the morning.