Marxman are a great politically edged rap band with Irish tinged melodies. They are from Bristol U.K not Ireland as reported in an early post.
Check them out:
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The Irish Front. lol.

Someone already mentioned them, Altan is a great Irish folk band... I'd start with "The blue idol", great album.

Fave song: "Caide Sin Don Te Sin" from the "Runnaway sunday" album, soothing vocals, good production, great lyrics, and overall beautiful song.