There is a 15% discount for Interrail tickets at the moment. http://www.seat61.com/InterRail-pass-guide.htm
is a guide for where you can go with one.
The Interrail Sale runs from 1st February until 31st March 2017 at 22:00 GMT (23:00 CET, Midnight EET).
You can choose the start date for your Interrail Pass. The first day of validity must be within 11 months of your date of purchase.
These Discounted Promotional Interrail Passes are non-refundable and non-exchangeable.
Interrail Premium Passes and Interrail One Country Passes for Denmark, Finland, Norway, Poland, Sweden and Switzerland are not included in the Interrail Sale.