An implementation of the HTML alignment algorithm of STRAND:
P. Resnik and N. A Smith. The web as a parallel corpus. Computational Linguistics, 29(3):349-380, 2003.
This also contains an implementation of the Gale and Church sentence alignment algorithm:
W. A. Gale and K. W. Church. A program for aligning sentences in bilingual corpora. Computational Linguistics, 19:75-102, March 1993.