Do you know any very good songs in Latvian, Belarusian, Portuguese, Slovakian, and/or Czech?

I am a language nut. I absolutely LOVE really good songs in foreign languages. I'm trying to complete my collection of songs in European languages first. Right now I'm lacking good Latvian, Portuguese, Belarusian, Slovakian, and Czech songs. Can you suggest any songs that is in one of the stated languages?