This coming weekend, from 15:00 UTC on April 6th to 15:00 UTC April 7th, you can participate in SP DX Contest. You find the rules here.
The contest is organized by Polish Amateur Radio Union (Polski Związek Krótkofalowców) in cooperation with the SP DX Club. Amateurs around the world should contact as many Polish stations in as many provinces of Poland as possible. Polish stations use the following prefixes: 3Z, HF, SN, SO, SP, SQ.