Well, from a quick scan of (part of) my filk song index (adapted from the M.A.S.S. F.I.L.C. Index), I get the following filk songs written to Battle Hymn of the Republic:

A Modern Folksong
APA '45 Forever: or, The Teenfan Tyrannty Song
A Song in Praise of the Warriors of the Middle Kingdom
Battle Hymn of Hastings
Battle Hymn of the Rebellion
Glory, Glory, Science Fiction
Hordes of Mordor
Quark's Song
Salute to Shadowcon
The Battle Hymn of the Helpers
The Battle Hymn of the Ranapublic
The Filker's Bronx Cheer
The Hacker's Battle Hymn
The Techfan Tyranny Marching Song: or, APA '45 Forever
The Theme Song of the U.S.S. Enterprise
The Thermodynamics Final
TurkeyCon '77
Westercon 23: or The Con-Coordinator's Lament
1, 2, 3, 4 ... Testing
The Bradbury Hate Song
The Klingon Diplomatic Corps Marching Song: or, Imperialism for Fun and Profit
The L.A.S.F.S. Marching Song
The Teenfan Tyranny Marching Song
Westercon 23: or The Con Co-Ordinator's Lament

I don't have the lyrics for most of these, but I thought I'd toss it out here anyway...

For those who don't yet know, filk refers to the folk songs of science fiction fans -- which often involves writing new lyrics to existing tunes, as in the above cases.

Jesse Weinstein