If your Eurail pass is valid in Poland, you can take advantage of the discounted lounges at Warsaw and Wroclaw train station. You can also use your pass to travel easily from Krakow to Berlin by IC bus.
You can obtain benefits locally by showing your Eurail pass, or you can contact the specific benefit company in advance. The discount benefits only apply during the validity of your pass. Free passage on trains, busses or ferries is only valid on travel days.