The Scottish Arts Council (see [4.17]) has suggested having a new national anthem written for post-devolution Scotland. However, a number of existing songs or tunes could be used. Here's the most frequently suggested.
God grant that Marshall Wade,
May by thy mighty aid,
victory bring,
May he sedition hush,
and like a torrent rush,
Rebellious Scots to crush
God save the King.
Flower of Scotland is also used in an official capacity as the anthem
for Scottish Rugby and Football and I believe it is also used at the
Commonwealth Games.
See also [9.3.1]
Dawning of The Day (The Corries)
http://www.corries.com/
Freedom Come All Ye (Hamish Henderson)
Hamish sees this song as more of an international, rather than
national song. Lyrics at
http://www.dickalba.demon.co.uk/songs/texts/freecaye.htm
Scots wha hae (Burns)
For a' that (Burns)
Auld Lang Syne (Burns) (there are two tunes)
Scotland the Brave (Victorian Celtic twilight nonsense)
Caledonia (Dougie MacLean)
http://www.dunkeld.co.uk/
Alba (Runrig)
http://www.runrig.co.uk/
Both Sides the Tweed (Dick Gaughan)
http://www.dickalba.demon.co.uk/songs/texts/tweed.htm
'Hey, tuttie taitie.' (Scots wha hae) is a Scottish tune of such antiquity that there is belief in many quarters, (including Burns himself) that it was indeed the very battle tune used during the Wars of Independence.
Parcel O' Rogues (Burns)
Loch Lomond (traditional)
See [9.3.8]
No gods and precious few heros (Brian McNeill / Hamish Henderson)
http://www.b-mcneill.demon.co.uk/