I went to this last year. It's in Katowice in Poland and was ace. Couldn't fault it except the beer (Carlsberg, wtf).

This year's looks ace too:

http://www.festiwalnowamuzyka.pl/en/

(Kolsch, Gonjasufi, Terranova, Ben UFO, Shagaan Electro, Jackson and his Computer Band, Mouse on Mars, Bokka, Dixon)

Tickets are under £30 until the end of April too and if you look at last year's lineup, this year should be a good 'un. I'll probably go.