In The Mysticism of Sound the Sufi Hazrat Inayat Khan (who I consider a spiritual father) wrote:
\"The Supreme Being has been called by various names in different languages, but the mystics have known him as Hu, the natural name, not manmade, the only name of the Nameless, which all nature constantly proclaims. The sound of Hu is most sacred.\"
Hu also has a special significance for me as I studied sufism for several years and our Thursday evening practice included zikr - or devotional chanting - of which Hu, a name for God, was chanted. If you do a bit of googling you\'ll find \"Hu\" also integral to Eckankar, Egyptian theology, and other traditions.
(On a more humorous note, we learned from a beta tester that HU has also come to mean online and in texts to \"hookup\".)